An interesting article. I have some experience with colonias as there's one near me and I have been through and near others. What's a bit confusing to me is that this doesn't sound like a colonia at all (although it is referred to as "formerly" a colonia, perhaps confusing me further). Colonias are typically areas with no incorporated entity at all and often on land not platted for residential development. This leads to a near complete lack of infrastructure. Without water, sewer, paved roads, or even street addressing, colonias tend to have significant safety and health problems just due to the realities of exurban population concentration without the infrastructure to support it.
That's not the case here, though---the area is apparently a planned residential development with an active developer and property owner's association. To the extent there are infrastructure issues it's probably a result of underregulation of residential development, a widespread problem in Texas that the article nods to. But that's a whole issue aside from the "haven for illegality" accusation which feels like far more of a scare story than a reality. Still, crime in areas like this can become a significant problem... impoverished people in marginal living situations (e.g. RVs parked on rural lots) tend to be very attractive targets for theft, and that starts a feedback loop of escalating violence and worsening conditions as residents feel forced to defend their livelihood and shelter---and therefore get trigger happy with firearms and aren't able to hold down jobs due to the time they'd be away. This has visibly played out in the San Luis Valley in Colorado, for example.
The situation here seems fairly optimistic, though, doesn't it? The school district seems responsive, the POA is funding law enforcement. It looks like a community that's maybe on the edge of this downwards trend starting, but that's taking active measures to stop it. What they need from the state legislature is probably more funding and perhaps authority to incorporate, I'm not sure how that works in Texas. But that doesn't look like what they're going to get, because the legislature's dominant party has decided to make it an illegal immigration story.
The detail that this is playing out in "Liberty County" is, of course, a wonderful one. It invites a comparison to libertarian/anarchist development efforts that have often failed in interesting ways, but then this doesn't seem to be one. The leg seems invested in it not coming off that way, either.