Ancient history time (and OT), but the whole final chapter of the war in SEA wasn't the result of weakness on Nixon's part so much as because he had lost all interest in trying to win it: by 1972, he was just trying not to be the one who lost it. The Democrats called the game as being useless and I think they were right.
Yes, we abandoned our allies to their fate, but they were abandoned by Nixon as much as by the Democrats. You had to be there, at the end, to know how peculiar our effort had gotten.