"I don't own any supports on this account"

assume worst case scenarios, he's not actually a smug but a mediocre player who is average at mid, bad at everything else whilst you are a great player who is great at everything.

you can go support and let him mid, then you have an average mid and a great support Deny him the position and you have a great mid with an ill-fitted support.

In the end come down to your attitude to winning.

.>_> yet the era of mage supports has gone by? velkoz support, annie support, lux (assume she is a support anyways), karma (imo is a mid laner)...

You can always be nice, but you don't have to give those people what they want. If you have pick order and you want mid, take it. They can pick unconventional supports if they wish, as long as they do not troll.

Everyone should be able to pick any champion they so desire, for as long as don't intentionally troll -- until party roles are defined by rules.

That said, you can't give trolls the roles they want. That's like negotiating with terrorists -- which is like throwing virgins into volcanos, or sacrificing food to the Elder Gods: It may give you temporary relief, but it hurts you in the long run.

Up to you if you care more about winning or about playing your role. If someone says he's a smurf, I would lolking them and check if they speak the truth. If so, I will let them have whatever they have, if not... It depends on my mood.

I always look up their ranked stats or match history on a site like lolking, then name the supports that they clearly own and ask them why those don't count.

If people don't want to play support, they can ask someone else to. There's no need to lie about it.

Sometimes last pick doesnt mean noobs, maybe he/she duo with 1st slot. And IMO, who is good at every roles is not really good at any roles. (Of course, I meet some people claim Mid/Top/ADCs then feeds hard. Every things can happen)

I, at the very least, have two supports.... which is bad but I at least know that i'm not completely helpless.

His assertion isn't plausible unless he's below level 10.

Annie and Soraka cost 450 IP. Janna, Alistar (used to be free with YouTube or Facebook sub to Riot games), Fiddlesticks, Morgana, Taric, and Zilean all cost 1350.

Janna and Morgana are very powerful supports that serve different roles later. Annie all-ins are nasty. You have multiple solid-to-top tier support options available in less than a day's worth of playing. This guy just doesn't want to play support (which is odd, this isn't DOTA, supports in this game can translate into a lot of things).

I usually fill which gives me a lot of ADC or support but it's up to you what you want to do with this guy. He's probably not going to be very useful no matter where you put him. I don't care enough to fight over roles but if someone else wants to mid and he's last pick then support he is, just tell him to have fun and make it a kill lane there if he prefers.