Rey's big attack is massive damage anyways, so its not like he will take a big 299k hit from her. Its just way too soon to worry about how he sucks.
My guess, there will be a fix and it will be to Kylo. Brutal assault grants 10 siphon and stasis strike? gives 20 siphon and they both read "to the end of the encounter". Knowing how CG has operated in the past with play testing, it would not surprise me if his UA, when activated, will reduce his siphon stacks from 100 to 30, probably creating an infinite loop for his UA since it lasts 3 turns.
They will then do what the OP is asking for and FIX him.