> Homomorphic encryption hides data, not computation

Data is computation.

  x = challenge_byte ^ secret_key
  if x > 64:
    y = hash_memory_range()
  else:
    y = something_else()
  return sign(y, secret_key)

That snippet has nothing to do with homomorphic encryption. It's just the same kind of challenge-response AIM and many others were already doing in the 90s.

You seem convinced that homomorphic encryption is some kind of magic that prevents someone from observing their own hardware, or from running Chrome under a debugger. That's just not true. And I suspect we don't share enough of a common vocabulary to have a productive discussion, so I'll end it here.