I don't see anger in "LETS F**ING GOOOOO". It's just a comment that says "let's do X" in impatient and enthusiastic manner.
I realise this wasn't part of the dataset, more making a point that written language without context ( and sometimes even with ) is subject to huge amounts of reader interpretation.
PS Hope they will never begin solving philosophy problems with ML.
One interesting question, though: if "LETS FUCKING GOOOOO YOU DINGBAT" were meant to be a combative insult, would someone still add a bunch of O's ("GOOOOO" instead of merely "go")? My intuition is that if combativeness were intended, "let's fucking go, you dingbat" would be more likely than "LETS FUCKING GOOOOO YOU DINGBAT", but of course it's a bit hard to say without that context.