By pure averages: 9 attacks hitting on 4's, wounding on 3's is 3 successful. Again, by pure average that's one failed save in two rounds. So the Ark equiped Basti could be rolling into the third battle round with zero or 2 wounds on it - still not bracketed.
Once in melee the Ark gets to attack in each of half of the battle round, because melee can activate on opponents turn.
If there is an objective in the middle of the field (so the SE basti can't just run away) then the Ark equipped Basti is going to win by pure math, put it in coalesced (where thunder lizard is) and it's advantage gets greater (because now the solar engine is doing 1 damage).
BUT, that's all absurd. That's not how power level is assessed. I don't see every running the Ark in the current scroll if I'm trying to win (I'm sure I will run it for fun, I have mine magnetized to switch out).
I was just trying to say how you could argue for it. mortal wounds and the Ark attacks twice per battle round (of course SE can do that in TL with a command...) is the only argument I can think of.
If I'm trying to make it useful, I guess I'd try to put it in Starborne Thunderquake battalion with a EotG, where my goal might be to get into melee to soak up attacks, and then the battalion ability, EotG, and Slann spell can heal every turn, possibly really keeping the enemy locked in combat with it and bouncing off the 1+ save as I keep healing it back down so it isn't bracketed.