Any chance he counted to "one" and then wrestler came out of criteria and he got to "one" again, but to the audience it looked like a two count? Officials know it is important to be in position to see NF points--a couple of seconds can make a huge difference in a match, as you've expressed.
Videos are useful to evaluate a call.
Two separate posters asked the same question on two separate Topics. I think without a video the official needs to be given the benefit of the doubt on this call. Even with a video, it is the call that the official made. I think your son is a very good wrestler, so nothing at all against him. But, as I said in a previous post, the wrestler who loses the match will see it as a bad call, and the one who won the match will see it as a good call.