I’m guessing you’re referring to this post right before yours:
That’s almost definitely just company policy that everyone works 12 hour days and some captains/office personnel lose their shit if you ever report working over your designated hours (even if you actually did).
The only legally mandated 12 hour rule I’m aware of applies only to deck officers on towing vessels. No one else on tugs has work hour restrictions unless the tug is required to be STCW compliant.