Its just an internet meme to "do not move the cat" while its sleeping, because its Anthropomorphism, becauae typically if you distrub a human baby, they're gonna cry, so not disturbing them is a polite thing. So they're extending this principle to pets.

Realistically, you can pick up a cat and move it somewhere and they won't be bothered, they'll just go back to sleep within 10 seconds. (Only applies to your cat tho, don't touch a stray cat, they might bite)

Disturbing the cat results in no attacks. It just means that the peaceful cat gets woken up from their cute nap, which is bad.

how bad could it go

this bad