Lets take a step back... what one person sees as just a dog barking in excitment, someone else may see a large threatening dog aggressively barking.

Being around big dogs my whole life, I can see something like this going way out of hand and the owners dog being taken away for just being a dog. I've had friends worried about my GSD, when they LOVED people! I hate to see someone not understanding a large breed and assuming that the dog is aggressive because it's barking.

My point is, NONE of us were there except for the OP, so what do we really have to go on but what they say?

All dogs have different barks and levels of excitement, and if the owner says they are being friendly, perhaps they are. We shouldnt all assume that this one side of the story is the only truth.