Conceptually, yes, it is correct. But, with the electronics in the humidistat controller, it may need neutral to be wired to it, and may not like the by-pass on-off switch. You'd have to read the specifics of that switch. If the humidistat switch was entirely mechanical, then yes, it should work, but it may have electronics which would need power. It would normally say if it needed neutral. You may have to call the manufacturer to verify it wouldn't be damaged by power on both ends when it wants to be off unless it says something in the tech sheet.