Modern, in moreh nevuchim, the rambam is trying to convince people to keep mitzvos which they don’t understand, because they have a yatzer hora not to.
This yatzer hora needed to be dealt with, and the rambam tackled this task.
In mishnah Torah the rambam clearly understands chukim as laws without a revealed reason, as he writes in the beginning of rosh hashana “af al pi she tekias shofar gezeras hakasuv…”
Moreh nevuchim wasn’t written to be abused. Actually, it was written specifically for heretics like mendelssohn.
Chazal say that goyim harangue us for keeping mitzvos without revealed reasons (see rashi in beginning of behar). Mendelssohn is in that category.