Well, I personally would find this a bit of a waste. With rune words, it's usually a problem of not having enough of the runes or not wanting the rune word :p . And oftentimes finding one with the right number of sockets is just as easy as finding one with one too few.

But it should be easy enough to check... *goes to check*

Funny how rare socketed items become if you look for them ;) .

But I can confirm that socketed items can not be selected for the socket reward. If you have any evidence to the contrary, though, I'd like to hear it.