I certainly wouldn't go near any other riders, hell, the last time I was out I rode on the wrong side of the road when going past a pedestrian.Perhaps he was concerned at their distance from him.
I've barely been out, but oncoming cyclists passing at under two metres presents a low enough risk as to not worry about.
Might be a bit unfortunate if the other rider coughed as he passed.
A couple of years ago I was gobbed on by a rider who didn't do a shoulder check before parting ways with his phlegm, just as I was coming past.
Thoroughly unpleasant, I was raging, but it was unintended.
If that happened now I'd have no option but to do a violence. Possibly with the use of a bicycle frame as an offensive weapon with superior range as well as defensive capabilities. As the police dragged me away I'd probably shout a one-liner from an 80s action movie.