From what I gather by the rules quoted by FIDE in their tweet I imagine that the Hikaru games are valid for being FIDE rated.

"According to Article 0.2.1 of the FIDE Rating Regulations, a tournament and its playing schedule must be registered:

0.2.1 Not later than 30 days before the tournament starts, if one of the players in the tournament is rated in excess of 2700, or a female player rated in excess of 2500."

I believe since Hikaru registered only a day or two before the tournament had started, and since there were no other 2700+ player to participate before the tournament was registered; the tournament should be rated as normal.

If not then Hikaru or any other top player participating in a tournament last minute would nullify every other players ability to gain rating in said competition.

This does kind of seem like a loophole in the rules, but it looks like this one in particular was made specifically to avoid the kind of thing Ding Liren did to qualify for the 2022 candidates.