i used to know how to make a unit unable to move (not frozen) so u can order it to move, but it wont, but now i forgot how to do it so if anybody remembers plz tell me
You could also disable doodad state on certain units, that way they would be commandable, they just wouldn't do anything.
You constantly move (teleport) it to a place where it cannot be teleported to. That will give the order "Stop".
Or you constantly move it to the place where it is already. That also gives it the order "stop".
Both are good methods. LegacyWeapon's method is better because it allows you to stop many units of the same type at the same location from moving in the least triggers.