While I may be new to the hobby, I would NOT buy fish if I felt they would not be happy in my little tank. I did a lot of research before getting the loaches. The fish profiles on THIS SITE actually say that yoyos are fine in a 10 gallon. I also searched the archives and found several threads that agreed with that.
In my searches, I also saw a thread or two where people argued whether or not yoyos were fine in a 10 gallon. This is obviously a point of contention. However, obviously MANY PEOPLE DO FINE WITH YOYOS IN A 10G. How do I know this? It wouldn't be arguable if they DIDN'T. It would be a simple "no."
There are no rules in fishkeeping, there is only advice and personal experience. Therefore, "'they are okay in my 10g so it's fine'" IS a good argument. I felt confident saying this, because I've seen other, more experienced people saying the same thing.
A 10g is all I can physically fit in my apartment, or I would have a larger tank. I admit that it is not the perfect environment for my fish, but they are healthy and happy, and I wish to share this experience. I think that's only fair, no matter what my level of experience.