Draft Pick: What should you do if someone steals your role?

Hello. I just experienced being assigned the position of MID in draft pick, only to have someone spam "Mid mid mid," then pick mid, and have their premade defend them by saying "He said mid first," and i'm like... uuh... this is draft pick. So I am curious, what is the appropriate course of action according to Riot rules? Am I allowed to pick my role, go down mid lane where there is undoubtedly a person unwilling to leave there, and just do my best to play with them on my side in mid lane? I'd probably get reported by the premade, but is this acceptable behavior according to Riot rules from my end? I can ignore them, mute ping audio and mute them, and keep playing to the best of my ability. I truly hope that I won't be told to just "go with it" and play the role that I didn't receive, which would basically mean to let the troll do whatever he wants. Draft pick assigns rolls. I'd imagine that takes priority over someone trying to forcefully take the roll they're awarded. So yeah, I'm just curious from a Riot perspective, what is the best possible thing I could do, short of giving up my role and letting rude people win.
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