letting criminals loose in other cities, Houston in particular?
That is silly, of course. Criminals in Houston or anywhere else in the country can freely travel wherever they want. Of course the people in the rest of the country can travel wherever they want as well. Many travel to Texas on business, to visit family or friends or for vacations.
Fwiw, here is a story of 6 criminals from Houston who decided to ply their trade in KC. Of course these are just the tip of the iceberg as there are undoubtedly many others that didn't get caught or that we aren't aware of:
https://www.justice.gov/usao-wdmo/pr/six-houston-residents-indicted-conspiracy-steal-bank-atms