That's true.It seems like the Prime Directive is a Starfleet rule but they've definitely come down on folks outside of Starfleet who were interfering with alien worlds, including John Gill, Nikolai Rozhenko, and even the Ferengi running a con in the Delta Quadrant. Kirk armed the tribe in A Private Little War to counter Klingon interference. They don't want it happening at all.
"Angel One" tells another side, but I don't believe this other side meshes well with Picard's attitude in "Homeward." From "Angel One":
DATA: Mister Ramsey is correct, Counsellor. The Odin was not a starship, which means her crew is not bound by the Prime Directive. If he and the others wish to stay here, there is absolutely nothing we can do about it.
Of course, that's not really an anomaly, because canon often doesn't mesh well with itself.
