What’s the difference in terms of safety if an airplane (a SE or a WB) flies at FL100 or FL360 in a controlled airspace? It is safer only at higher levels, isn’t it? Ok, those fellows that died on a B737 collision in Brazil thought the same.
If there is not a medical urgency or any other situation that affects the aircraft performance, a pilot doesn’t need to rush looking for an immediate landing after a (rapid or slow) depressurization. Everyone knows that a jetliner can fly very well (nicely and safely) at FL 100 otherwise I can’t imagine how short sectors (including in congested airspace) can be made. Searching for options in that area it’s easy to find out that VVTS, Brunei or heading to HKG aren’t better than a 180 degrees returning to SIN, coincidently SIA home base, a place with a good support, several hospitals and an extra airplane as well.
Crews must not fly an airplane considering what a lawyer would say. They should consider first what is the appropriate option for everyone involved, including their company … this is part of their CRM I suppose.