Strangely enough, that’s exactly why I would consider Rob to be in more danger than Parvati. The tally of current players still in the core game (not counting EoE) stands at 17 - 10 men, 7 women...
Dakal: 5 men, 4 women.
Sele: 5 men, 3 women.
...so in any mixed-gender alliances I would expect the female members to apply pressure on the male members to next evict a male - if only to (a) demonstrate loyalty to their alliance over gender loyalty, or (b) prove there isn’t an all-male alliance in the works.