Did they pay these lawyers by the word? I haven't read the Act creating the Board, but
@castlecake2.0 the documents now identify both the authority for prohibiting COVID-19 mitigation (safety and sanitation of structures in which private businesses operate) and the enforcement penalties ($250 civil fine for every day of violation). As far as private businesses within the district, the Board states that it has declared that "society is harmed by discrimination based on COVID-19 vaccination status" and generally prohibits requiring documentation certifying vaccination or post-infection recovery or imposing a testing mandate to gain entry into the buildings.
Unlike the other sections applying to property owned by the district, it doesn't prohibit requiring masks or other face coverings.
This is just based on a very cursory reading in an area I'm not too familiar with. If anyone else can weigh in, I would love to know your take.