PROTIP: The film "On The Beach" and the TV series "Lost" are not documentaries.
And your 'caveat' is purely a hypothetical one, and not relevant to your argument. Why? Because the chances of everyone on a plane not being heterosexual are billions to one against; especially taking into account the fact that LGBT people are essentially a minority; Even a Saudia flight will have at least a few non-Saudi Arabian & non-Muslim passengers.
...and besides, one two-letter word completely annihilates your argument: Bi. As in the 'B' part of the 'LGBT' equation.. The chances of there only being Gay men and Lesbian women on board are thousands to one against, which further annihilates your argument.
Oh, and speaking of annihilation, one plot hole in your argument: if a 'major worldwide earthquake' had killed the rest of the Earth's population, why hadn't the resulting tectonic shifting done the same on that island (or at least the resulting tidal waves generated by the 'major worldwide earthquake' drowned said 200 survivors; it would have, the way these things work!)?! People on the other side of the world heard the explosion of Krakatoa (West of Java! [/pedantic])
Or mayhaps that's the nub of your gist: you've been watching "Lost" too many times, and not only confusing fiction with reality, but you think that said 'island' - as per TV series - is a kind of 'Waiting Room' to the Afterlife., and everyone on said plane had actually died. Ergo, your question is purely hypothetical, and I never deal in hypotheticals; only Reality.
...but the trees are epileptic, though. X3
@Mr Smith
"What about the bisexuals. It's not a fucking two horse race you know!"
"MLP:FiM"'s Lyra & Bon-Bon. Just sayin'. [/shipping] [/innuendo] /)^3^(\ X3 [/smartflank]
http://mylittlebrony.wikia.com/wiki/Lyra_and_Bon_Bon