There's not a massive difference in F/F (a few hundred kg/hr), so yeah what you say may well be the case depending on the diversion time.
However that's nil wind. The wind can be markedly different at EO LRC ceiling (say, around FL250), and 10,000ft (in the depressurised case). This is the thing I've seen many guys ignore when they sweat on the CPE, which for the Bus assumes you're both single engine and depressurised, as if it's the same thing as an ETP with an engine failure but not depressurised.
I agree with your sentiment regarding contingency plans, etc. I wouldn't like going below the ETOPs flight plan fuel either (my attitude to fuel planning is certainly never going pave me a path to Management
). It is planned that way to cover the worst case and if it's not your lucky day, you might need every drop of it!
Certainly in relation to the original post and the info we have, it doesn't seem the crew did anything untoward by continuing as they did. Christmas Island is a flight planned ETOPS adequate (Cat C airport) too, and honestly my A330 would have to be in a very serious condition to head to a tiny speck in the middle of a massive ocean in the dark of night (as QF and JQ flights to HNL are conducted) with one 2000m runway, a non-precision approach, PAL, no ATC, and landing on one engine. Majuro is similar, but marginally longer.
PKMJ, Majuro, is classified as a company approved, Category A, Adequate Airport.
Well that's an interesting difference! Strange that it can be considered cat A for a JQ A330, but cat C for a QF A330, especially when you look at the airfield and it's facilities.
I mean, QF and JQ A330s are one and the same. As I say, I'm speaking from a QF perspective. What you just told me is weird.