It happens from time to time. I never bother to actually type in the chat when it happens, if I had been your toplaner I would have gone "fine, let's duo top then". If I had been the support I would have taken a champion that can farm safely under tower 1v2 and just played the game.
Being in promo or not doesnt matter. I just pick my champion, pretend nothing unusual is happening, 90% of the time the guy who said he was trolling is the one dodging.
The very rare times noone dodges and the guy actually trolls, I consider it's some "well spent" time given to help the community get rid of one of their most toxic players.
By the way it doesnt prevent me to actually learn and improve or have fun in the game, I just ignore the troll and try my best.
The only thing I never do is : negociate with terrorists. This guy wanted you to dodge, and you did it. Now everytime he's autofilled, he will do the same shit. Because you gave him what he wanted, you showed him he could do that. And because the game never actually happened, you can't even report him.