Both of them are classless acts. It's a really misleading and ignorant assumption to think that its the same people complaining about both things.

Greta could be considered a joke but that doesn't mean that she should be attacked. The President could be considered a joke but it doesn't mean it's classy to boo him at a public game.

This is part of the problem with social media. "The same people that..." type of comment is ignorant. You have no real idea if it's the same people or not. There are billions of people in the world posting on social media every day. Almost all of them are random and blind to you and incredibly, incredibly unlikely to be the same people from one comment to the next.