Glad Keir is pretty much back to normal by the sound of it. Hopefully you are too now that a few days have passed.
I’m with you on the not letting go, very frightening. Snowie was bitten by an English Bulldog - grabbed Snowie's lip when Snowie went to greet it - he was a puppy, offleash area. Screamed. Terrifying moment for me. He recovered very well, still happy go lucky. But I have noticed as he ages - now 6 yo - that he is more wary of some dog breeds (Rhodesian Ridgebacks, Border Collies) and particular dogs that have been nasty to him (we see the regulars on our walks). On a separate note, I guess I have the (misguided) impression that guide dogs are immune to other dogs, that being in a harness and doing a job somehow keeps them away from nasty dogs. Re your turning to food for comfort: true Labrador you are! Like many of us...!
It’s good to hear that there’s been no lasting effect on Keir. The not letting go bothers me too. I know a lovely rescued staffie who normally gets on well with other dogs, but he’s the only dog I know who can destroy a Kong...