It's not like Omar had much of a choice, though if I were him, I would have certainly tried to convince her to give me the idol. It's possible that Lindsay was okay with Omar going home, and therefore did not want to protect him, but I don't think she could see the forest because of the giant Jonathan tree standing in front of her. In her defense, while Jonathan wasn't the greatest threat to win with Omar still in the game, he was the biggest obstacle to her winning challenges, even if it is unlikely that he could solve a two-piece puzzle, especially in a calorie starved state.
While Maryanne got Omar out, a big assist has to go to Drea for exposing him as the threat that we all knew he was. I'm surprised that it has come to this, but Maryanne is the only player left who understands that at this point in the game, you need to be getting rid of the people who could win at the end. Mike and Jonathan both are stuck in "whatever gets me to next week" mode. Lindsay prizes challenge success over the game. Romeo just wants something to eat.
I've been hoping that I was imagining things, but the editing has favored Maryanne all season. While I think anyone but Romeo could conceivably win at the end, things seem to be trending Maryanne. For anyone else to win, they will need to engineer the vote that eliminates her. Maybe everyone else will wake up and remember what the objective is to actually win.