As a Hufflepuff, I wholeheartedly accept this headcanon. Hufflepuffs are the ones who care about people - helping people and taking care of people. So it totally makes sense that the RoR would've been created by a Hufflepuff.
--------No seriously, you don't understand. I am 24 years old. But you tell me when and where and I'll be first in line with my glasses and my wand. --- this is what I've wanted since the first Potter movie!
This is funny, but I always got the implication from the books that there had been people trying out for Seeker, but none of them had been very good. So McGonagall stepped in because she loves her House team.