Personally, I would like to die the way the painter did because it would mean that the last thing i did before I died was to create something so holy with my bare hands. Since that would be the last thing in my mind before I die, It would guarantee that I will be born in a good place where I can practice Dharma and practicing Dharma is all I want to do from the start. The amount of merits gathered by painting such a holy image can only be humongous. By the way, this type of thangka is called a trungrab, and it features the lama and all his previous incarnations around him. It is said that to worship to such a thangkha creates the merits to cause the teacher's life to be long and the teacher's works to grow and flourish far and wide. Every person who gains attainments or get blessed by the image will add up to the merits of the painter. Besides, dying right after doing something meritorious is so much better than dying while in a state of mental confusion and pain and selfishness, which will definitely lead to the 3 lower realms after passing away. To me, dying early after doing meritorious deeds is much better than dying later, after accumulating many negative karma.
This person is so lucky actually to have passed away, because if he did not and if he did anything negative, it would be a complete waste of that persons' meritorious actions as the negative action would have overwhelmed it and prevented the person from going to a better rebirth. Pick which is better: gain merits for the day and then die immediately, or gain merits for that day, and then live on but in the process, do a lot of negative actions that incur a lot of negative karma, to the point where it is for sure that the next destination is nothing short of the 3 lower realms. I pick the former in more ways than one if given the chance. Why? I do not want to be a burden to others, nor do I want to continuously create suffering and bad karma for myself. However, many people will not see it as this way as they think that suffering and death is always bad no matter what are the circumstances. But this is not true from a deeper point of view due to the reasons that I have just given above. What society thinks is right is not always right.