You can't leave reviews on the Xbox store unless you have bought the game.
So there is no justification of deleting reviews.
You can. You just need gamepass and can review it with as many profiles you want (only have one gamepass and could still play and review the games with my kids profiles).
I can rate it right now and have not installed it because I'm not at home and only have the s with me that has not enough space (without removing the games for my kids).
Btw, if you watch the numbers, it seems more like they have removed ratings from players who did not play the game, else the overall rating would not be less than before removing ratings (wouldn't make sense to reduce the overall score if they would actively trying to change the score)
Btw, there is even a review here that says "couldn't download the game" ...
And also, I can add a review for the premium edition not in gamepass, so I'm not sure you even need gamepass. Seems more like just an Ms account.