Dealt with a player that didn't want to support (another autofill rant)

So I just finished my placements (Got placed Bronze 1 4-6, go figure). I won 1 game of ranked then I go in for another. Some guy decided to lock in Riven even though it was CLEARLY support that they got and I got forced to dodge because I'm not going to lose 20LP over someone who doesn't want to play it through. They made it VERY clear that they weren't going support and everyone told them to dodge instead but they decided "Nah :P I'm gonna pick my AMAZING %57 7 game winrate Riven just cause I don't feel like dodging".

Ironically, I got placed as support the game after my placements and kicked ass as Naut (I main ADC and play mid secondary but I can always fill so). This autofill issue is so stupid because there are people like this who really don't care about losing others LP just because they didn't get their intended role whether or not it's 3LP, 10LP or 20LP. Like, either pick a support that's braindead or dodge. What's the issue in losing 3LP and waiting 5 minutes? If you honestly think you're so good at your main role that'd you pull shit like this then losing 3 LP should be irrelevant.