Yes. I'm not sure what your point is, though -- I already agreed that adding port knocking is
like making your password longer, and there's nothing magical about a 64K alphabet. It just
means that a single knock gives you about 16 bits of entropy, as compared to 6 bits from a
random ascii character, so 1 knock gives a bit less than 3 (good) password characters. Or...
you can just use a 4096-bit key and be done with it.