He generally is, unless the situation is that:
1) It's something generally stupid, like this thread is, and
2) if the author thread is either stubborn or extremely rude (also like you are)
Fun fact: You can roll back to any system restore point, ever created on your computer. So, no, Paint.NET will not stop you from doing a system restore, even if it is the most recent.
Secondly, installing a program will always change the registry, and, say for example, it messed up the registry, and you couldn't use system restore? System restore is used as a way to stop any chance of "permanent" damage to a system due to one reason or another, and I'm sure it'd be worse if there were people genuinely complaining about a program messing up their computer rather than just one self-abosrbed person whining.
Seeing as you know so much about programming and the do's and do not's, why don't you make your own image program yourself?
I would say more, but honestly, due to the huge amount of bile coming out from people thinking they know what is best for a program and for what Paint.NET can do recently, I'm not honestly suprised by the way this "moron", as you say, has acted.