I usually don't like byes as those 4 spots could have given someone else a chance. I'd much prefer 64 and 6 rounds for everyone, or 32 and 5 rounds for a more level playing field, but on this occasion, directly after a major, I don't mind it. When you see the likes of Schoofs and Paquet directly enter a Premier event not even ranked inside the top 150, it badly needed it's star seeds to give it a bit more credibility, especially in it's first year, and with Svitolina still playing in New York on Thursday, and particularly Sabalenka still playing on the Sunday, you'd think they'd have been pretty likely to withdraw late if they had to start in round 1 on Monday or Tuesday, allowing more 150+ers like Kerkhove in directly.
I think if any of those top 4 seeds were to withdraw now, without yet playing a match, then a LL can still come in - there's been many recent examples when a LL replaces a seed and gets a bye (and takes over the seeding), but I'm not sure when the cut off is for that to happen - whether it had to be before R1 was complete, or if it's just a case of having to be before the seed was due to play. Had there have been a LL opening then it would have been between Frech and Muhammad.