A statue of a Buddha is not only a statue, Buddhist revere statues as Buddha themselves. So in the eyes of Sri Lankians, of course it would cause a furry!.. It's like someone going up to Obama and kissing him on the lips - they'd be jailed too, wouldn't they? So in that case, it's the same as how the Buddhist in Sri Lanka feels. I gotta give it to them though, being so strict with their beliefs and culture,.. it sends a message out to the world and therefore, deters such acts from happening again. Someone had to be the "victim" of rules, so these French tourists were the ones. If the officers didn't take action, people will continue doing it. Once someone takes action, it lets others know that it is wrong to do what they did.
However, the tourists were probably not in the wrong either. They probably don't know the symbolism and representation of Buddha statues to Buddhists, and therefore, for photography sake, posed as what they did. Many of us see a cute street figurine or mockup on the street and do funny poses next to it.. so it would be the same in this case. It was out of pure ignorance. I guess they learned their lesson, and might even pay more respect to Buddha statues from now on.