Yes sometimes Yo-Yo aren't aggresive, but they will usually be aggresive, or atleast slightly, and I wouldn't want to take that risk if I were that person. While I have never ever heard of an aggresive cory!!!
I am not saying Yo-Yos are bad, infact they are one of my favorite fish, its just that they are known to be aggresive, also my friend has an aggresive Yo-Yo. But if markiey want to take that chance, then go ahead!