A bit of a click-bait title, but it is true that Microsoft has bought Activision-Blizzard. You can read the announcement on their website.
I assume that this means that Microsoft now owns the Swat franchise since Activision-Blizzard bought it from Vivendi-Universal back in 2013.
In terms of the Last Resort mod so far we have been lucky to not have lawyers knocking on the door. Some studios don't like mod makers. Hopefully the new owners will also leave us alone since we are a benefit to their meager Steam and GOG sales for Swat 3.