Austin would actually be a good play. It's a big enough city, and it has a very tight-knit community with a good amount of civic pride. I think leagues are starting to realize that you can fill a venue with that. Give Austinites something to call their own and they will. Give Houston a team and you're just an experiment in a place that even saw an NFL team once come and go.
Demographics also play a part in it. The NHL, unfortunately, is a league barring little appeal to folks who aren't white. Austin, especially for a southwestern city, is real real white. Now, you might go, "there's more folks of x demographic in Houston than in all of Austin!" and you'd be right: but part of building a fanbase is infecting a community with interest. That interest is harder to get in Houston, because most people aren't gonna care, and the collective impact will be much smaller if it's not relevant to the majority. Whole other conversation, but hockey is mostly a non-starter for non-white people in the US, unfortunately.
If I had to name a close comparable, it'd be Nashville. A city stocked with enough wealthy-ish white transplants who might not be as sports-minded from the outset, but embrace the team because they want to embrace the town. Give them a team to be proud of and they'll go nuts. Austin is like that. Houston is more like Atlanta.
