What can i even do to stop people like this?

For the sake of trying to conserve a decent game just switch with them instead of two people being stubborn and ruining that game entirely. Then report them afterwards

It's either he backs off or you'll be in bot lane with him.

Report after game if he doesn't go mid.

There isnt any money to be made from adding lobby kick so dont expect a solution until riot finds a way to profit from it.

Remind me again why we don't have a decent report system outside of the end-game lobby? Or why "vote kick" isn't an option for lobbies yet? (certain number of uses obviously)

just go mid then report them after, nothing you can do but dodge and that's never fun