I have eaten canned cabbage (#10 survuval cans)that was over 30 years old and stored badly, in the garage in a moderate climate (So.Cal coast), and it was edible, I could have served it to people and they probably wouldn’t have asked about it.
The E.R. Doctor might have had a question or two! I am surprised that the cans did not explode. I don't think I would have the courage to try 30 year old cabbage... fresh cabbage does me in (or out)!
Oh my. That might be provably the absolutely worst thing you could possibly eat in a sealed fallout shelter, even if you were by yourself.