In an interview for Fighthubtv.com, Munoz addresses that possibility with the wonderfully noncommittal "I'll cross that bridge when it comes," followed by extensive praise of Silva. This non-answer doesn't mean that they won't fight, but it isn't encouraging, either. Black House fighters seem particularly loyal; Silva refused to make a title run at 205lbs because that division belonged to Lyoto Machida. Munoz agreeing to the fight could antagonize the unpredictable Silva.
The most famous case of teammates refusing to fight is Jon Fitch and Josh Koscheck. They are unquestionably the second- and third-best welterweights right now, but their friendship thwarts one of the best fights in the division. Fights between camp members is a contentious issue, though, as the rift in Jackson's between champion Jon Jones and Rashad Evans has shown (the heat generated in the reactions between the two would provide an excellent build for a fight, should the UFC decide to book it again). Many gyms view training partners as a family, and agreeing to fight is akin to betrayal. For a team with as much success as Black House has found, is it worth the risk?
The UFC's hands are tied in these situations. They cannot force someone to fight without consent, no matter the quality of the proposed matchmaking. When the possibility of the title on the line, though, the incentive for the challenger rises. Kos/Fitch relies on a title shot, not the belt itself. Munoz would be gunning for Silva's title, his belt, and ending his 14-fight winning streak. Perhaps that would be too much temptation for Munoz.