Wow, lots of misinformation here.
A. Privately owned/public use airports can receive federal funds, but they must be part of the NPIAS (
National Plan of Integrated Airport Systems).
B. It doesn't matter if the federal dollars were used to build the hangar, the FAA grant assurances apply to the entire facility. By accepting a federal grant the airport agreed to abide by the
FAA Grant Assurances. That money comes with strings, and yes its legal.
C. The FAA will initiate investigation and enforcement actions if they receive a complaint that an airport is in violation. The enforcement actions can include requiring the airport sponsor to repay any previous grants and prohibition from receiving future grants. In short, you may be jeopardizing the future of the airport financially. Most airports cannot afford to upkeep their infrastructure without the FAA's assistance. Airports have been violated for improper use of airport funds, non-aeronautical use including RC operations, drag racing, storage of non-aeronautical items on the airport, and outright theft of federally funded equipment. This isn't theoretical, it has happened and will happen in the future.
You can scream freedom and privacy all you want, but the truth is if you are operating from an airport that has received federal funding, and most public use have, you are subject to the FAA's policies.