In no way does that suggest that what the church in this story is doing. The difference that your "legal training" failed to impart to you is that what this current church is doing is well known to everyone, including the government. It's not harboring if everyone knows where they're at.

-Harboring is conduct that substantially facilitates an immigrant’s remaining in the U.S. illegally and that prevents the authorities from detecting the individual’s unlawful presence. (U.S. Court of Appeals for the Second Circuit)

-Harboring is conduct that clandestinely shelters, succors, and protects improperly admitted immigrants. (U.S. Court of Appeals for the Sixth Circuit) 

-Harboring is conduct that provides or offers a known undocumented individual a secure haven, a refuge, a place to stay in which authorities are unlikely to be seeking him. (U.S. Court of Appeals for the Seventh Circuit) 

In other words, harboring is when the person doing the so-called harboring is doing it clandestinely.