I'm going to use your comment to lean into the 'this doesn't make sense' as compared to other creatures /magics so some of this is not totally relevant to your question but it is relevant to similar sentiments, so let me throw this out there: The monks do not care if you sell your soul to a deity. - If you're a machine-spirit, you've unknowingly sold your soul to Gorumdir. If you're a foul necromancer/Mystic, the taint on your soul means Aeriel is going to bump you out of the golden city anyway (and also these magics are traced back in their origin to an Angueldaemon, that being Iblees)
Sorvians do not lead you to cheating death; they teach you how to create funny little guys with a bit of mud, some blood, and a little soul energy, which is a thing that regenerates naturally. Golems (aren't very well written) feature nothing of consequence other than soulbound golems, which are technically a temporary (In a relative temporary sense) torture cage for a soul that will inevitably be broken.
Frankly, the original intent behind Tawkin was that it was so esoteric and wicked that even learning OF kloning was a PK clause, but naturally this was amended for fairness.
I view this not only as more fair for homunculi but also a move back toward the intended tone of the FA - The prior iteration of Tawkin is the reason we have the 'you can only have two grafted limbs', not for balance, but because Bogodan's clay was actually an artificial symbiotic parasite that attached to your body and ate your life force.
The spirit of it has and always has been something esoteric and taboo that has gradually (And i take partial responsibility for this) been whitewashed by its usefulness as a clinic feat and wacky little freaky friend maker, and including Homunculi in the PK clause is not only a step back toward the intended tone of the piece but also reinforces the idea that making these kind of things shouldn't be so widely accepted.