I HATE it when off leashed dogs come up to me and my leashed dog. It pisses me off. Nebo is socialized and he loves other dogs...but does the dog love him? And dogs react differently to other dogs. I cannot always guarantee my dog will be friendly to strange dogs either. Nobody can.

And how do you know this dog wasn't socialized? What kind of dog was it? Some dogs just do NOT like other dogs...that doesn't make them vicious. It's not quite a normal dog encounter either....think about it...you're on a leash, probably feeling the stress from your owner being nervous, then some other dog runs up at you freely...it's not like any regular playful encounter.

I can see this owner keeping the dog on a very tight leash, or maybe a halti/gentle leader to have better control of the head. I don't think it's quite fair to have the dog muzzled just because other people let their dogs run loose.