If it's only the inside diameter that shrunk by 100% then it's only the hole that's gone, not the whole thing. The wall can still be as thick as it wants. If it were the outer diameter that shrunk by 100% then the entire thing would be gone, as you rightly said.
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If it's only the inside diameter that shrunk by 100% then it's only the hole that's gone, not the whole thing. The wall can still be as thick as it wants. If it were the outer diameter that shrunk by 100% then the entire thing would be gone, as you rightly said.
I'm just giving them the benefit of the doubt :D
How much can you squeeze through no hole? I have more doubt than you :)
I did the math. It's about the exact same as you can squeeze through the thing if it did not physically exist at all.
My conclusion is that whether the inner or the other diameter is the one that shrank only affects aesthetics, not functionality.