poor impulse control and a lack of long-term thinking and an inability to take others’ feelings into account

And what is stopping you from just saying that, rather than using a pithy pejorative with a side order of pop psychology? Or even “emotionally immature” rather than needlessly infantilizing him by pushing the age comparison down to “attitude of an infant”? It’s not just brevity. On some level you must want to express disdain for his behaviour.

I (seriously) do not see this as any different to “he hurt a few people’s fee-fees”. That guy chose those words to convey his disdain for the people Linus hurt. He could rationalize his dismissiveness just as you have, via “children are more sensitive” or whatever, and it would be equally spurious.