I should clarify what happened here a little.

Kicking somebody because they are currently trolling or griefing in a game, to prevent them from doing it further, is potentially okay. (Caveat: In my experience many players are quite bad at distinguishing griefing from inadvertent poor play in the heat of the moment, and you may well be held accountable for misjudgements.)

Kicking somebody in the pregame of the game after they maybe trolled you, in a game where they have so far done nothing, just because they happened to be on the same team as you again, is Not Okay.