It's still a non issue. As others have pointed out even non-knockback abilities like Grappling Hook and Force Pull will remove the knockback-immunity, at which point you just use a legit knockback and you're done.
It's really the easiest HM fight there is, no enrage timer means you can beat him in greens. Just use your brain when putting the group together. If you want to argue class comp, how about bringing a Juggernaut tank to Revan with no stackable force-reduction cooldowns to eat the instagib Force Lightning.
There is an enrage on HM Malgus.