Chiefs vs Steelers--2 pt try

[Kansas Ref]

There was a holding call made against our KC left tackle on an edge rusher on Pitt in last SUnday Playoff Game. The result of the call was that it disallowed our successful 2 pt try that would've tied the game. Many fans are saying that the such call should have been ignored because the Pitt player was falling down anyhow. Even a HS football ref told me that he would've passed on the call.
Am I missing something here? Do NFL officials call games tighter than HS level refs? Would it have been reasonable to pass on that call? Or was that call really a call that a normal ref would've made--despite the gravity of the situation?