If the message they’re communicating is “no” and not the exact details of why they’re saying no, “I don’t have time” is perfectly adequate. Everyone isn’t entitled to the exact details of why someone is refusing to do something. I’m not telling you if I’m refusing because I have severe diarrhea.
Saying you have no time when it’s actually lack of energy is just poor communication skills, it’s not about being literal.
If the message they’re communicating is “no” and not the exact details of why they’re saying no, “I don’t have time” is perfectly adequate. Everyone isn’t entitled to the exact details of why someone is refusing to do something. I’m not telling you if I’m refusing because I have severe diarrhea.
I would argue saying anything except “No” is poor communication skills.
If you aren’t willing to negotiate then don’t give them anything to negotiate on.