Could the Jailer have been killed early?

Let's say that after Cataclysm, we discover he was behind the Lich King and is currently behind Sylvanas' val'kyrs, and the Argent Crusade/Ebon Blade decide to deal with it early. Could we have stopped him?

His plan fails if Argus is not killed (but Argus does need to be killed), but even if he is left to rot in the Maw with barely any Anima, his minions will still bring down/weaken the covenants (at least the Necrolords, Venthyrs and Kyrians), and Denathrius can still supply him with a lot of Anima. But it seems his plans can be thwarted.

The Jailer had Domination, allowing him to neutralize the Primus, the main fighter of the Eternal Ones, and generally, anyone he met directly. The only way to block it was in Zereth Mortis, unaccessible without the Sigils, and it should stay unaccessible. That means the Jailer was nearly invincible until then, as he could oneshot anyone attacking him. Is there any way to kill Zovaal without allowing his plans to come within inches of victory?