It's a very strange fruit found in Asia. And it's very much an acquired taste - stinks like an over ripe corpse in a drain.
Some people may follow the ban and NOT continue eating it, but many more who don't care much about the ban may try the fruit and like it.
Therefore, the fruit ban, which actually publicises the fruit, may result in an increase of people who like it.
This is vague. Lets get precise. We need to consider the ban in terms of it's existence as a substantial cause, because then we can determine what effect it will produce.
If the ban is the substantial cause of the flourishing of the banned thing, then a ban on an object will only give rise to the flourishing of that object - which is patently ridiculous. Consider the following:
In your example the ban on the durians could be seen as a condition for some people to discover & subsequently enjoy the fruit, but it could not be seen as a substantial cause of that enjoyment or the subsequent spreading of that enjoyment by those people to others. This is the important point we must grasp here, the misunderstanding of which leads to your wrong view & harmful inaction. The substantial cause is always the same 'substance or type' as the effect. So the substantial cause of someone coming to enjoy durians could be them enjoying it, or something similar to it, in the past, maybe in a past life. But the effect of the ban would be the same substance or type as the ban - ie it would bring about a decline in the consumption of durians. If the durians were to suddenly take off as a treasured delicacy world wide, this would be because of the enjoyment of the people who discovered it, as supported by other conditions such as democracy, which is also not supported by undemocratic bans!
The ban on Dorje Shugden practice may bring the practice to some people's attention, but it is not a substantial cause of it flourishing. The substantial cause of the practice flourishing is faith in the practice. This faith inspires an individual to practice sincerely, set a good example to others, work to make the practice available to others etc. However the effect that the ban, as a substantial cause, gives rise to is a reduction in the practice. With this clarity we can see that while it is possible for someone to become a Dorje Shugden practitioner by hearing about the ban in the media, investigating it further & subsequently developing faith in Dorje Shugden (spelling it out like that makes it sound unlikely eh?), the ban is not the substantial cause of that faith. It is opposite in nature - going in the opposite direction. It is out of faith that our hypothetical person will have the opportunity to go to a Dharma Centre, meet with qualified Teachers etc. The ban is a substantial cause of none of this and it's only a condition (in this specific imaginary instance) in very small part.
The ban is not even a necessary condition for the flourishing of Dorje Shugden practice, like water is a necessary condition for the effect of a plant to arise from its substantial cause of a seed. If you remove the ban then you do not remove the faith of the practitioners, you do not do anything to slow or prevent any of the conditions which promote the growth of Dorje Shugden practice world wide. In fact it is easy to see how the ban much more readily brings about conditions which are conducive to the destruction of faith (how many people do you know like that hypothetical person in the example just given? How many people do you know who have lost their faith since the ban?). Given the harmful & unnecessary nature of a ban, why would we then support it or consider it beneficial simply because of the unlikely event of someone hearing about, investigating & developing faith in the practice through hearing of the ban?
You use the word 'may' (& 'possibly' - sends shivers down my spine! I wouldn't trust my lineage to a 'possibly'!) a lot, which in itself shows on some level you know the ban is not a substantial cause of the growth of the practice. So you have to ask what is. In what circumstances would those effects actually arise & when would they not? What is the cause, that is to say the substantial cause of someone meeting with & engaging in Dorje Shugden practice? What are merely conditions? What are necessary conditions? And what are their opposites? Your lack of clarity is dangerous. Someone might believe that water is the substantial cause of wheat growing & so end up starving to death! Or someone may think that the presence of Jews in a country is the cause of that country's misfortunes & so try & exterminate them. It is very important we are clear about causes & their effects. Proximity does not prove causation, & it certainly doesn't prove substantive cause, which is what we need to be crystal clear about.
Given that the ban is not a necessary condition for the substantial cause of faith to arise, but is a substantial cause of the destruction of the lineage, we should act to oppose the ban. I'd add that given that the ban stinks like a durian, we should act to oppose it wrathfully!
All this is very interesting as it shows how a simple misunderstanding can bring about huge disruption. We need to eradicate our ignorance of the precise meaning of the Dharma through debates like these. Again - I greatly appreciate this opportunity to reduce & finally eradicate my own.
BTW:
Extending your reasoning it would be a good idea to ban Buddhadharma altogether as that will make it flourish. Does that sound sensible?
Excellent reasoning - spot on.