Yes, this is behaving as designed.
Originally I was on the fence on this, but now I am definitely moving in this direction.
Disabling a macro disables all its triggers, as well as any implicit triggers (such as within a macro group or a web trigger), but it can still be executed explicitly, by Execute a Macro and via executing the macro explicitly via its UUID in AppleScript (not sure if I have implemented that, but that is my design intention).
If you want to disable a macro even from this sort of intentional explicit execution, add a Cancel Just This Macro action to the front of it or otherwise disable its behaviour.
Please consider this thread locked as far as any further discussion on the pros and cons of this policy (ie, don't make me actually lock it), but feel free to discuss alternative ways of disabling the actions within the macro if desired.