This is one of many judgement calls that can or not be penalized. The player safety mindset behind rules like this results in the officials getting guidance that if it is "close" penalize it in order to establish the spirit of the rule. Aside: thought the hit on the QB going out of bounds probably should have gotten a flag based on this logic.

"A receiver attempting to catch a pass who has not had time to clearly become a runner. If the player is capable of avoiding or warding off the impending contact of an opponent, he is no longer a defenseless player"

In the context above looked to be a "good" call albeit in the "good old days" this and the QB situation would have been good defensive football.

This link explains what a "defenseless player" looks like in a variety of situations: https://operations.nfl.com/the-rules/nfl-video-rulebook/defenseless-player/

Another aside: Would love to see a TV broadcast in which they had a graphic with the rule and how it is to be enforced ending with "now let's see the play in slow motion" (with no commentary describing what is being shown) ... and then back to discussing the play with someone who actually knows the rules and what the NFL (ACC or whatever) have told their officials about applying it.