Does this imply that the rapture won’t happen on any day any man or angel predicted it, and suggest that these crackpots are either delivering a “no rapture today” message from the Lord Almighty or else embarrassing Her into putting it off?

You should check with the laws in your state (or your insurance agency, if you have a low enough deductible.).

Just because the grocery store puts up a sign that they are not responsible for damages doesn’t mean they aren’t. They have a first amendment right to lie, and a game-theory reason to do so.