I personally think it's just another Media Opportunity and that it'll devolve into politics.
The anthem hasn't been played on TV for several years, but everyone knows all the media will have their cameras zoomed on the sideline for whomever sits. This is just another song, a prelude, in which they can observe that everyone's standing for it and then probably kneeling for the anthem, which will lead to heated discussions about whether standing for the "Black Anthem" but not for the anthem is OK and What It Means.
The NFL and the players' union have bigger fish to fry around how a season will even look like. If a player decides to play can the NFL hold them to "reckless behavior" clauses that include no Ubers and no dining out? If they test positive is that a "football-related injury" if they got it at work or is it going to be like MRSA and the flu, which were NFIs that teams don't have to pay for? If someone pops positive on their Monday test after a game then who needs to be notified and what position groups need to sit out?
All these questions are so far unanswered. They can't really even talk about asses in the seats yet. LA is on fire with the coronavirus. Santa Clara is already deemed worthy of the state's watchlist. Houston is talking about repurposing NRG stadium for a field hospital again in July.
They have more problems now than bringing on yet another group of contractors, stage guys, sound guys to complicate the situation with singing at all.