I rather dislike Putin, as I've stated a fair few times, however I suspect you'll find it difficult to find where I've taken such a stance. I dislike him as he's a bully.
Personally, I'm an advocate of allowing Ukraine to use western weapons further into Russia, but the caveat is that it's not free rein - it has to be within a framework.
Ukraine may want to use them however they wish, yet that's never going to happen. I doubt it's less about Russian retaliation, and rather domestic politics!
Medvedev has already shown recently that he (and Russia) can show a level of composure when discussing nuclear weapons, so it really isn't on the cards...
... unless something absolutely drastic occurred. But the use of these weapons, in the rear, will only help weaken Russia further and help bring about a speedier end.