A man's opinion of what an "A+" dog is, is only valuable if the man has actually produced A+ caliber dogs that have defeated top shelf dogs.

If we can even get passed that hurdle, then comes the matter of honesty.
He was either honest or he wasn't.

That said, you can't tell shit from a kennel accident (especially with a male with a bitch).
Other dogs being around also doesn't mean shit, as many truly great dogs aren't all that aggressive and will happily walk passed angry dogs.
The only thing that matters is what they do in a pit with a dog of the same sex.

I would stop speculating, and (if the dog is okay) let him heal for a couple weeks (get him used to you) and then roll him with a talented dog his own weight.

Then you will have your own opinion

Jack