How is that different from the moonies or harry christners? Nobody is screaming to put them in jail. And good luck going to the Appalchia. They don't look to kindly on trespassers.
The Moonies, who were Christians, and the Hare Krishnas, were mostly Americans and short on resources. I think if the US ever saw hundreds of highly organized and well-financed foreign missionaries doing all on their power to lead vulnerable people from Christianity, there would be an uproar and Christian evangelicals would be at the head of the pack.
I think you were right to characterize these hypothetical missionaries to Appalachia as trespassers. What about real missionaries to Himalaya?