I don't know, and am loathe to guess. One could say that if they weren't spraying the field, then they didn't have a legitimate reason to be there, and there is an argument to be made for that. Additionally, arguments might be made that flight close to structures, or persons on the surface, presented both a legal and safety issue.

There are arguments to be made in support of such an operation, however, but may not be well understood by anyone who doesn't operate in that environment. When it's one's home turf, so to aeronautically speak, it's familiar ground, though clearly not free of consequence.