why didn't they shutdown engine 2 when the low oil temp and high pressure readings first appeared
1st, take with a reasonably large pinch of salt anything on the program last night. Leave to the final report, as and when that appears.
However, to answer your question, why on earth would you shut down an engine for HIGH Oil Pressure, and LOW Oil Temperature? As the program said, these are the opposite indications to those you might expect from an engine in distress (you would expect a problem to give you Low Press / High Temp).
You tend, in general, not to shut down an engine for one indication. Whilst a Fire Warning might be an exception, modern systems are "double loops" and so a Fire Warning is not a "single indication". Whilst the LOW temp / HIGH pressure might add up as a double warning, they do not give an indication that an IFSD is required.
I fly the more baby Airbii, and the only references I can find to these sort of warnings is the "OIL LO Temp". The only recommended action is "Delay Takeoff" - useful mid-Atlantic! It may be they got this caution, and deduced the "Hi OIL Press" from the gauge? Or maybe the 330 / Trent does have such an ECAM?
In summary to this, and presuming the program got this right, I would never imagine an IFSD being considered - although the crew might want to hunt around for other "problems". Suspect these were caused by (very) cold fuel spraying onto something in the Oil circuit, or a sensor etc.
as the documentary implied but not saying otherwise, forget to that the cross feed was on after engine 2 failed?
I think that is the moral of the incident... Without blaming anyone, everyone now treats the X-Feed with more respect than before. To Open it to Balance Fuel, should IMHO, only be done with a stopwatch, some calculations, Fuel Page up, and papers down! If in any doubt, close X-Feed until you can understand WIHIH...