I think that if someone has problems being friendly with coworkers then they may have some issues of their own that need to be handled. I'm not suggesting that they invite this guy or any other person over for dinner, but developing professional relationships is something that helps a workplace to be more productive.It can be dangerous to not make assumptions also. Being friendly can be dangerous. Ignoring a problem can be dangerous too.
Treating people with respect is fine. There is a difference between being friendly and being polite. The OP doesn't want to be friendly. He just wants this guy off his back without being rude about it. He wants to be polite. That is in the OP's interest. It gives no consideration to the interests or needs of the annoying guy. I think a rude friend would be beneficial to him. He needs someone to let him know when to shut up and unclench. This guy needs the acceptance (respect) of his peers as much as anyone else.
If you are rude as opposed to polite, what have you accomplished? The guy wasn't trying to start a fight, but now you have anger in your workplace. It is really hard to actually work somewhere where you are concerned with the politics that you have to start playing once you start a argument.
If you develope mutual respect you can make more suggestions without hurting each others feelings/egos. What good does it do any of you if your rude friend takes a verbal shot at the guy. If you can't find a real adult way around the problem then perhaps the guy who talks to much isn't the one with the real work stopping issue. You don't have to be nice and like the guy. Just be nice so you can get your work done.
If this guy is truly trying to be a nuisance then you should handle it with your HR counselor. If they see that he is talking to much it should show in his productivity. If this guy is your boss you will either have to put up with it or find another job because the ladder climbing method will most likely end with you on the losing end.