This is a very old argument, and doesn't really do much to advance the debate and the hobby I am afraid. This argument is the exact opposite - and equally frustrating - as the "no way no how never" tang police argument. I find BOTH of these arguments frustrating (what you are proposing, and the tang police) and neither do much good I think.
Obviously, their are major behavioral and ecological differences between Kole and yellow tangs, but elaborating on them would be pointless in this situation.
You are more than welcome to do what you wish with these nice decorative animals, that is true.
However, not all tanks are suitable - even forgetting about size. A tank without live rock makes this an even worse situation for many tangs. The original poster, it seems, might like to hear all the possible risks, as well as the "do what you want, its not the ocean anyway" argument. At the very least, they may be losing money in putting one in there if odds are it will not do well.