Leaning a bit more toward "against", though I could not care less about any of the games Activision-Blizzard has produced. MS has enough money to either grow its teams, build a network of second party devs, or acquire new start-ups to do it the way Nintendo and Sony have managed so far. Instead, and after two decades of mostly failures, it has decided to fall back on what secured its quasi-monopolistic position elsewhere: Impose its model by buying up its way to the top via investing funds that its competitors could not dream of, obtained via activities that have nothing to do with videogames; and accelerate a consolidation process that could very well change the landscape for the worse (see Hollywood consolidation).
Were MS to agree on keeping the franchises multiplatform, unlike what it did with Zenimax, I would not give the thing any importance...but cutting off millions of people, depriving the audiance of Playstation of titles that they have been used to getting for years, simply to tackle Sony, is, frankly, a move that should be opposed: Instead of creating IPs under your banner, simply make sure that existing ones are no longer available to your rival. Plus, what would stop MS from waking up one morning and deciding to make Capcom, Ubisoft, or any other publisher an offer they could not refuse, knowing that neither Sony, nor Nintendo, could lock horns with them financially?
Anyway, it is still videogames, a simple entertainment industry, so it is not like it is that serious of a matter...It's just that you start wondering whether there are any rules that govern the field to prevent such a potential concentration of power.