I am pretty sure that even Sugar's DF is useless at some level of haki. at the end it depends on the user and the DF for example yes Hancock cannot turn some one into Rock if he has stronger haki than hers.
Wait, is it stated that you have to haki than the user?
this isn’t a haki be haki situation where the stronger one wins. This is a df vs Haki. Why would the The DF user’s own haki affect whether their hax ability affects the other person?
by this logic, Boa’s body transmutation is literally POWERED by haki??? Tf? Now Boa’s DF itself requires Haki energy to get stronger?
does that mean that now ALL DFs require haki to get stronger? Holy shit. You are now implying that at the end of the day, Haki is actually the only real power in this universe. And DFs are just weird ways of using haki.
btw, this could be very interesting but, it’s also a lot of people’s worst nightmare that in the end, DFs really don’t mean shit.
For now, until that is confirmed, we shall s just take it as case by case. Law just happens to be the hax that can be countered by Haki. Sugar did NOT have better haki than ALL those people she turned into toys. That’s impossible. So your explanation there needs more tweaking