You're conveniently forgetting that Houston is in the 4th largest market, one that the ACC currently has no piece of. Do you think ESPN might want more carriage fees or streaming eyeballs in Texas? Remember, the ACC is a conference WITH a network already. Footprint is even more important to the ACC. Houston has 40,000+ enrollment. It has double the endowment of UConn according to Google. It has wealthy and influential donors. It's tier 1 Carnegie.
Your response will probably be that Houston doesn't offer a large enough share of that market. However, with the trajectory of the program (they brought in their best recruiting class ever this year) and coaching staff, Houston is ranked again this year and definitely not inconceivable they'll be ranked at least one of the next 2 years. With success comes better recruits, fans, and higher market share. Especially since they've had past athletic success; this is a dormant program with woodwork fans and obviously a large alumni base in the market.