Can they: Yes.
Should they: No.
Comments are, by their very nature, ephemeral. Once they have served their useful purpose they can be deleted at any time.
If any valid but long-winded academic discussion takes place over many comments, then often a moderator will move them aside into a dedicated chat room, where the thread can be continued without disturbing the regular Question/Answer areas.
If any thread runs completely out of kilter, then there is absolutely no reason to ever revive or preserve it. Usually simply deleting the comment thread will put an end to any argument, as it is difficult [by design] to ping someone on Stack Exchange in order to continue it.
The number of times a deleted thread would ever need resurrecting is vanishingly small. Resurrecting any argument or disagreement would benefit no party involved. Airing dirty washing is not the purview of Stack Exchange.
If one was needed for moderator review, it is already within their ability to see the entire thread. Moderator decisions are not normally shared in public, though the individuals themselves may be notified of any decisions made.