There are other ways to get zetas. Through packs, anniversary gifts, raid shop, TW and TB IIRC. There is probably a few in the quests as well. They've also been collecting it from the fleet event when they got HBD, and from fleet currency.
With the change to raids and simming, it may count completed raids for you, even if you dont do damage.
This isn't an obvious case of a hacker, they haven't shown any sketchy unlocks or (GA) battles. Take their Thrawn for example, they have 5 Phoenix at 6*, but he is still 5*. Why not just hack the battle and get the 6* ?
It's a suspicious account, but no clear hacks.