Hanlon's Razor is worse than useless if the target is aware of the principle. Then they can be malicious and play it off as incompetence. Which works especially well when they are also surrounded by genuine incompetents. They can also be, and often are, malicious and incompetent.
It's like saying "if it's white, fluffy and has four legs, never assume it is anything but a sheep". If the wolf knows you're applying that logic, what happens next?
Hanlon's razor is a great counterbalance to peoples' natural inclination of assuming people aren't dumb. The problem is when people divorce it from that context and assume it applies in general.
It's like saying "if it's white, fluffy and has four legs, never assume it is anything but a sheep". If the wolf knows you're applying that logic, what happens next?