Regarding religious acceptance, I've always felt that the idea of extraterrestrial or non-human intelligence would mesh well with the major religions. I think a lot off devout people would morph the idea of non-human intelligence to match that of angels or messengers. You can already get hints of that from some of the Republicans pushing for disclosure. Whether or not they're right in their interpretation, the overall concept of NHI would be accepted by a lot of people.

The biggest part of a controlled disclosure is preventing political conflicts and keeping the economy stable. If there has been decades of UAP/NHI recovery and research, then it could create tension within and amongst countries. We're always seeing tension grow between Congress and the DoD over the issue and public disclosure would just fuel distrust.

Any reveal of research and the companies involved could make for major fluctuations in the stock market. On top of that, I'd imagine there would be an onslaught of lawsuits with those companies to make research and patents public.

I wouldn't expect a basic disclosure to be catastrophic to the public, but it would be to the government and contractors. The hold up at this point is likely those involved trying to cover their asses to limit the consequences for themselves.