Who said she was a paid guard? I’m pretty sure my congregation’s security is all volunteer.
I assume an armed security guard would have to go through legal channels to patrol the church grounds and would likely be a paid professional so as to avoid liability with an “employee” of the church.
Based on what? It's a mega church, huge operation 10,000+ in attendance. They probably hire a private agency, and are a big enough profile that they regularly get threats of violence.