Removed from the game lobby. Bug?

Hello Board!

So I was in que for a blind pick game just now and I really didn't know what lane to pick. So the other guys picked their lanes first and I ended up in top lane. I asked the other guys in the lobby if anyone else could go top since I rather not play top. After a bit of discussion back and forth I got to play adc instead. Now this is where the interesting part comes, cause the guys playing bot were two premades and the guy going adc said it was fine for me to adc and the support did not agree. Anyway, I picked it, adc that is, and then all of a sudden I got kicked out of the lobby with the message "You were removed from the game", the que timer thing was reset and when I tried to que up again I apparently was penalized by the "system" with a five minute ban.

I don't really care about the ban to be honest. I'm just curious of what the hell just happened. Have I been a victim of some sort of admin/moderator power abuse (in this case the support player who didn't want me to go adc) or is this just a rare bug? In all of my, idk, 6000(?) games I've never experienced anything like this. Has anyone else?

Cheers, Moat Builder.