It costs $100 to list a free game on steam. And blizzard has sorted out the blizzard login stuff and store front integration with steam through overwatch.
This seems like it could be an easy slam dunk. It still is the best MOBA out there, it only struggles with player base. Throw it up for free, if it starts doing OK then maybe have a few programmers work on controller support for folks to play on steam deck.
Seems like an easy way to capitalize on something they already built.