It's just a cash-grab attempt with minimal risk - plaster together a game based on the current top genre and hope you get just a tiny slice of the market. If it fails, they've only lost a small amount of money and it's taken them no more than half a year to test the water. Saves them spending 2 more years on a game that may be DOA and when Battle Royale has fizzled out.
The problem they had with LawBreakers was 4 years of development making a game in a saturated genre that cost a fortune that in the end nobody wanted to play. They've done the exact opposite with this one at the expense of ethics, credibility and quality. It may make more than LawBreakers did even being free and cost a lot less money to produce but it's not done the studio any credit.
Boss Key Studios could've easily tried to make a decent single player game or look for a gap in the market but instead, once again they are trying to chase easy money in genre that is dominated by rivals even more prominent than Overwatch.