Well, his behavior might well just indicate residual or redirected aggression if there was an altercation. Redirected aggression can linger for hours after the precipitating event...I expect any cat who's been in a fight to be aggressive, snarly, and antisocial for at least several hours.
Have you had a chance to examine him yet? Look in and around the mats for blood or foreign matter, or for injuries around the matting. Check paws, face, mouth, tail, and belly for any signs of injury. Any bleeding, deep cuts, pucture wounds or signs of things like motor oil/grease/tar/road materials on the fur are cause for an immediate vet trip. Any stiffness or sensitivity is cause for a call to the vet for an appointment ASAP. A vet call will probably be a good idea anyhow (they may want to see him just to be safe), but it's very important that you get a really good look at him to assess any injuries now so that you know better what's going on.
At the very least, separate the two cats at least overnight. If he is, in fact, having redirected aggression, he could take it out on the other cat and cause long-lasting problems between them. Better to allow him the space to decompress in peace than to spend the next month (or longer) with one cat bullying and the other terrified.