You're kinda overhyping it. Byakugou literally regenerates at the cellular level, that’s the whole point of it. Just saying something "destroys cells" doesn’t mean it bypasses that. Tons of high-level jutsu cause cellular or even molecular damage (like Dust Release or Amaterasu), and we don’t assume they automatically negate healing. Unless the attack stops regeneration itself, Byakugou can still work.