To me it's just pure joy of having scored a crucial goal, no trolling intended. Also Griezmann seems like a nice person, he would not mock other players. Gerard Pique and Real Madrid players, current or former, do that, because they were on the receiving end of it for more than a decade. 2-6, 5-0, 0-4, 5-1...
Barca Twitter can post whatever they want and I dislike that kind of stuff, because karma is a bitch. The club is in a free fall, despite of the good run lately, there is a rat on board who snitches to the media, the club is ruined financially and the Messi uncertainty hangs in the air. And yet club's official Twitter page is run by someone who has the guts to troll other clubs/players. I'd troll back and shut any discussion just by reminding that person of that 2-8 that happened not too long time ago.