The rules are in place to protect the crews from exploitation by the employer.
They are also there to prevent excess fatigue becoming a major factor in an accident . Thereby also protecting the traveling public
There is a 2 hour Capt's discretion built into the limits to allow for unforeseen circumstances. In applying the discretion the Capt should take into account all factors including ,but not limited to , Crew Fatigue (of all pilots) , weather enroute and at destination, likely delays upon arrival , aircraft serviceability , stress levels , availability of alternative options ,
The rules clearly state that the 2 hour built in allowance may only be exceeded in an emergency . Getting home does not constitute an emergency
It's one thing to use discretion during a daylight flight but when you have been up all night, fatigue becomes a major factor, sometimes it's difficult to determine just how much sleep deprivation can cloud your decision making That's the reason the rules are there