What struck me most about their F4 pact, was that Rob insisted that nobody get greedy, and that they remain loyal

But this is a disingenuous thing for him to say, considering that he and Amber already at that point had a strong two-way alliance within the four-way alliance. Rob was getting greedy at the time he said those words -- rather than it being "every man for himself" at Final Four, as the four all agreed that day, Rob was already seeing it as Rombuh vs Rupert then Rombuh vs Jenna.

Rob knew even then that his alliance with Amber was stronger than Rupert+Jenna so as much as it's a good and fair thing to say, "Nobody get greedy and we'll all get to Final 4, when it is every man for himself," Rob was already set up so that he wouldn't be merely one quarter of a four-way even split of power. He knew he'd actually have half the power while Rupert and Jenna, with a quarter share each, would be primed to turn on each other.

This is the kind of thing I like about Rob's gameplay, though, and the kind of thing I hope he wins the game for.