If they are all models LC, then they have no damn business operating in the NAS mixing it up with manned aircraft. Not anywhere near an airport, a runway approach path, or within 500' vertically of anywhere a manned aircraft could potentially operate (and that's a lot of area).
Since models have been operating in these areas for a long time with very few problems, I have to say they do have business. In fact if operated comercially the FAA is willing to allow them to do so if they follow their proceedures. They have allowed ultralights to operate in the NAS with few restrictions, at one time without any restrictions. Although I believe you may be refering to commercial sUAS.
See and avoid is the key.