Since Starsector is a single-player campaign, all that matters is how well your ships can destroy the enemy AI.
As for Tempest against skilled enemy fleet, how good are your twitch skills? Can you dodge incoming fire from an enemy capital with Combat 10? Does it have enough firepower to overload a shield that can dissipate hard flux?
Hyperion is great as a flagship because it can teleport to an AI ship's blind spot, fire, do some damage with blasters or missiles, then teleport away. With a Hyperion, I can kill any standard AI ship even if it has Combat 10. I cannot do that with a Wolf, Tempest, or even Medusa because my weapon range is much less than the enemy, and I may need to beat down shields (that can dissipate hard flux) first. Enemy flagships with Combat 10 are fast, can regenerate damage, and their shots are even faster and hit very hard, especially missile salvos.
If I cannot use Hyperion against enemy flagship with Combat 10, I would use a much bigger ship, like an Aurora, Onslaught, or Paragon. Enemy flagships with Combat 10 are usually extremely dangerous opponents, more powerful than the rest of their fleet combined.
That said, AI Tempest is a very good frigate, and does not spike your fleet DP through the roof like the Hyperion. It can be relied on to flank and kill most enemy ships, or at least the best it can.
Hyperion needs double max capacitors (from Flux Dynamics 5) and good weapons and hullmods to really shine. I think the reason why my AI Hyperion does not die much is I give it lots of flux (20 capacitors give it lots of flux for teleporting and blaster use), Extended Shields for full coverage, and maybe Accelerated Shields so that shields are up almost immediately after a teleport. The main use for AI Hyperion is 1) capture objectives on the enemy's side of the map quickly and 2) another ship for you to transfer to after you launch your flagship's Reapers, and you need more.