Waiting In Line

I have to say, I loved that episode.  A lot of people felt it was too cynically manipulative, and that's entirely fair enough.  God knows I had that reaction enough times during RTD's reign of VERY LOUD MINOR CHORDS terror.  This time, though, it worked on me entirely, and has made me reconsider my somewhat low opinion of Karen Gillen as an actress (and as my friend Boo pointed out, it was probably the first episode of the series that actually sold the idea of Amy genuinely being in love with Rory).

Having said that, there is one thing that keeps rolling through my head regarding the ending of the episode (spoilers...)

There's some interesting debates going on across the internet right now about what exactly the ending to The Girl Who Waited says about Rory and, especially, the Doctor.  Some people are horrified that the Doctor could lie to one of his companions, offering her hope when he knew full well she would have to be sacrificed.  Others saw his actions as a welcome return to the ruthlessness that periodically raised its head during the original series.  And still more people judge his gambit as a fundamentally pragmatic one - he can only save one Amy, so it may as well be the one who hasn't been trapped alone for the better part of four decades.

For the record, I can see some truth in all three approaches, though personally I find it hard to get past the fact that the Doctor deliberately lied to someone in order to ensure they got themselves erased from existence.  Furthermore, I think Rory was entirely justified in complaining to the Doctor that "you're turning me into you!".  The Doctor insists it must be Rory's choice, but the choice isn't "young Amy or old?", it's "Leave young Amy in the TARDIS, or actively throw her out in order to bring old Amy in (the third choice is to let the TARDIS explode and kill them all, but presumably Rory isn't going to go down that route).  In other words, the Doctor offers Rory the choice only after ensuring the deck is stacked as heavily in favour of young Amy as possible.

That does feel out of character for the Doctor, actually, but that's not what's really got me thinking.  What I really want to know is this: given the deck-stacking mentioned above, what would the Doctor have done if the older Amy had gotten to the TARDIS first.  I wouldn't go so far as to say Tom MacRae was taking the narratively lazy path by doing things this way round - mainly because older Amy's choice to distract the robots to ensure Rory's safety seemed entirely in-character - but it does force one to wonder - just how "monstrous" was the Doctor prepared to get?