"Well this so called Commander (I use the term loosely in this case) needs to pull is head in... what a
!
"
If I was a commander and I was prepared to use discretion and the F/O was not then I would have the paperwork reflect that position. If the F/O (in this case) is genuinely too fatigued to operate then he should have no qualms about explaining his decision at a later time.
A decision to put 300-400 pax up in a hotel and delay the flight by 11 hours or so is one all crew members should take seriously and if you are just doing it to stuff up the company then, for me, that is not professional and will not get my support. If you are unsafe to operate due to cumulative fatigue then fair enough.