Was going to make the point above, Maven did it, albeit against HHH.
Logically speaking, you can't just boil this down to 'faces don't do this', if anything, that's the short-sighted '2 seconds thought' plan.
Ryder can make the point of 'You once used an oppurtunity like this to keep hold of a title' as was the case in Sheamus' WWE title run when he was allowed to choose his opponent. Different Sheamus, sure, but it would be a nice bit of poetic justice for Ryder and fans wouldn't hold the past event against Sheamus.
Ryder's character as a face is still defined ultimately as guy who was held down and used his internet show to develop a following. As an archetype, it is something a heel traditionally might do (minus the internet, but Miz and Big Show are two current examples). His character therefore allows some dexterity in this situation, he can make the point that he is never given a chance any more and wants to at least prove he is as good as the champion, he can even say something like 'even if I don't beat you, I want to prove I'm not a joke'.
Personally, don't think it should happen, it is true the effect is undercut by Sheamus being a face. You can get (likely) the same effect by facing off against Del Rio and making the point that 'if I can beat you, I deserve to main event Money in the Bank, so let's have a match and if I win, it's a triple threat'.
Either way, he should/will lose, I don't think it's stupid to suggest he gives himself a title shot, fans wouldn't begrudge him it.
I stopped watching Z! a long time ago (watched from 1-35 iirc), but I still wanted Ryder to win above most of the guys in the ring (I was shouting for Kane to win as he's been great recently and I've like everything he's done in that time), shows like this have the potential to be a lot more fun than if say Cena or Big Show had won as every segment and set piece isn't trying to sell me a PPV.