Don't do it, it's a pretty useless zeta. It may seem good on paper but it won't ge tyou anywhere of note in the game.
First, you'd have to completely adjust your modding to a full offence based set on all your Sith, which makes them only properly viable under that Nihilus lead.
In arena, it may do well outside of the top 200 but as soon as you start running in to Chirrut & Baze teams you'll get hit hard in the face: Baze's AOE attack does %health based damage, meaning he's going to hit all of your sith for a bulk load of damage.
In DSTB the rebels' special attack does 40% total HP damage, that means without protection as soon as your squad gets hit by this attack you're going to be on 60% health or less, making it even tricky in the "easier" early waves if the timing of their next attacks goes off right after the AOE.
It does not offer you any sort of protection, you don't get healed if you don't attack so with characters such as Thrawn, CLS, Zolo, etc. that can all stun, you are screwed.
So no, do not put a zeta on his leadership, it's probably one of the worst Sith leaders right now. Zader is still far more useful in different areas of the game, Zaul still has value in TW and arguably TB. Dooku... hey it's not a zeta, free dodge. Sidious leadership can even do really well in HAAT under certain conditions.
His unique on the other hand could be worth a zeta. But I'd move away from using him as a leader. You would be better off going with Rex lead, R2-D2, Thrawn, Nihilus & a good tank (General Kenobi ideally but Old Ben will do just fine). This team is perfectly viable for top 50 in arena and still utilizes your Darth Nihilus.