Plus, consider how quickly Reese picked up on how Jessica was trying to imply that Malcolm is gay -- almost as though Reese already had gay thoughts on his mind. The home is titled in both Justin's name and Jason's name, which you can verify at the courthouse. It was more of a remembering that he was gay. Somebody's working hard at the office.
Justin Berfield Bio/Wiki
I finished a third rewatch a month ago. For example, in Company Picnic , when Malcolm wants to make a move on a girl and wants Reese to stay out of the way, the first thing Reese says when the girl talks to him is "Sorry, I'm gay. But within my headcanon, Reese is gay and doesn't realize it.