[mhardcastle]

"Federally qualified health centers" (FQHC) are required to treat people regardless of ability to pay, and are able to provide preventive care to non-citizens. A list of such health centers is available here, and there are quite a number in Houston (where the subject of the article is based):

https://www.findahealthcenter.hrsa.gov/

Whether would-be patients are sufficiently informed of this opportunity is another question, but resources for preventive care are not completely unavailable to these folks.