Gears is owned by Epic not MS.
TBH people talk ill about MS and 'stealing' or 'buying' 3rd party exclusives, I don't think demanding owenership of an IP is better for anyone either.
That studio is then forced to create a new IP and hope it does well, or stick to exclusivity. With timed exclusive, at least after a year they can put the game on another platform, or outright have the sequel multiplatform. Mass Effect is a good example..
But I don't expect many to agree with me around here.