How often do teams do this? Because one incident comes to mind and it's Carlos Boozer.
Though a quick google search tells me Hauser's agent is Jason Glushon, and another search tells me his clients include Jaylen Brown, Al Horford, Jrue Holiday, so he probably has a good working relationship with the C's and has a vested interest in helping keep the team good.
Someone would have to break down the tax bill this year vs future years, but I would think it also makes sense as an alternative way to keep an asset, because he's certainly on pace for a big pay day next year, and the C's are going to lose him for nothing and be forced to replace him with a minimum contract player the way things stand currently. But if they sign him now, they can trade him away in a couple of years when their tax bill gets too big for a lesser salary, but someone more than the minimum (maybe in the $5-$8m range?). Pay more in tax now, but increase future flexibility.
Let's say the market for Hauser next year is $15m per year for 3 years, plus the $2m he's owed this year, that's $47m over 4 years. Sign him now to a $10-11m per year deal for 4 years?