I very much support the NHL going to Houston, but to go from nothing to fully running in a mere offseason is something that I don't think any American market could handle. The huge number of logistical hurdles, staffing necessities, and difficulties organizing a ticket drive would all take time, especially for a market already fairly well-serviced by pro sports as it is. NHL to Houston on a few months notice would be an utter crapshoot and mess. The same wouldn't be true with a move to any sizeable Canadian market, where hockey is already number one, where there already is a hockey season ticket base that you could immediately tap into (transitioning junior or minor hockey ticket buyers to the NHL is far more comparable than trying to get basketball or baseball fans to buy in), with entrenched media and corporate support all willing to jump on board an NHL team at a minute's notice, and with an ownership group with an expressed interest in acquiring a team already in place.
There's a world of difference that I don't think that could be waived away on a near-zero notice need for a relocation, which I would imagine would absolutely be viewed as taking priority from the league's perspective. And while there would be short term headaches for their divisional opponents, those would be molehills compared to a potential undercutting of franchise valuations if an emergency relocation resulted in a gong show.