US-P18.023ab ।US-P18.023cd ॥
In plain words
If the negation struck at something you already had, then mokṣa would certainly come out impermanent. So this negation denies what was never attained at all — like the ban on laying the fire-altar in the sky, and others of that kind.
Close to the Sanskrit
If what is already attained were to be negated, liberation would certainly become impermanent. Therefore this negation is a negation of the unattained, like [the prohibition of] the piling of the fire-altar in the sky and the rest.