OK who_cares, I misconstrued your original statement. However, you must concede it is ambiguous!
The A330 case neatly encapsulates the worst case scenario of only of two available fields, where one is almost directly behind you, and once beyond the PNR the WX deteriorates below ALT criteria.
I fully agree with continuing to PER in this case and doing whatever it takes to get the aircraft on the ground.
This scenario is quite unusual given the geometry of the SIN-PER and the geometry & distance of Learmonth.
The real question is what do you do prior to the PNR with the WX deteriorating below the ALT criteria?
And I am talking TTF's/ TAF's not hazard alerts use to determine the WX.