Not saying the mentor was in the right at all, but:

1) takes majority vote to kick someone,
2) they are your friend- did you coach them?
3) were you in a voip to help with mechanics?

Again, not justifying what the mentor did (assuming it was the mentor because you cannot know who initiated the actual kick), but if I see someone, the same person, doing things like constantly setting meteors in a place where two will land on each other and have a good chance of wiping the raid, after repeatedly telling them left or back instead of right, my patience will wear out and I will remove them.