I'm sure Westbrook can still play if he is allowed, this guy is super human, he might get tested but it should not affect him.
According to some article that has been posted recently, a player that will be infected with covid-19 will be out at least a minimum of 2 weeks, and of course it would not be easy to come back as training is necessary for a player to get back in shape, it's just bad for Westbrook but anyway at least this happened before the resumption of the season.
Well, yeah. He's still maybe able to play, but first he needs to get tested again for atleast 2 times after two weeks of his quarantined.
In other cases, it lasts to 2 or more weeks, depends on the immunse system of the carrier. Hopefully, with 16 days left before the NBA resume, WB should beat the virus before the resume day comes.

Every games is very crucial, and without WB it's gonna be a tough fight for Houston.