It probably will, at some point.
It will probably be MONTHS after the PC release at best, though.
And that's just in case agreements with Stadia don't extend that exclusivity period even more.
Still, apparently Stadia was paying companies a buttload of money for their temporal exclusives (going with the rumors we are talking borderline irresponsible amounts, sums that could fund the entire development a triple A release), so it's hard to blame whichever studio accepted the deal with them.
Honestly, I like "temporary exclusivity" cause it actually funds games fairly well while still ultimately being consumer friendly in that after some time the game will be available on other consoles.
That said, for me it isn't likely going to get me to buy a Stadia any time soon.