Possibly. Given the era that this started it is more believable. If a small group secreted it away in the 40s it wouldn't be that difficult to keep it secret. I think that is where all the UFO reporter discrediting came in handy. Anybody that was in the know didn't share and outside reporters were painted as kooks which discouraged others from speaking up. Throw in a few "disappearances" of credible reporters and nobody wants to talk about it.

Fortunately we can all talk to millions of strangers around the world in an instant now. Even the kooks can find a community to share to that might be able to coorberate their story.