There is no rational pattern for this group of people to be together other than to fail.
A few years ago, I would have countered with 'To romance Tila Tequila.'
I notice you put Ian instead of Erik. (Probably my fault.) Ian was actually a fine character until the end. His partnership with Tom was cool, and they ran Koror. His stepping down was bizarre. Caring what Katie thought. Giving the necklace to Natalie. Oh right, maybe they are the same.
How much did EPM want Tom to win Palau instead of Ian? So much?
My sleepy bad on the name switch, and edit-fixed. But as you noted, these spoilers create echoes -- and I think my subconscious was trying to agree with your message in post #8 (which I did read before replying). The person who could be some degree of threat suddenly leaves in the final stages, clearing the path for... As a one-time event, Ian's stepping down and out was weird, but could be (barely) rationalized. Erik? Youth, stupidity, and possibly susceptible to bribes of all sorts, so the line wasn't drawn at the time. (And then one of the all-time Creator's Pets won that season. We really should have been more paranoid than most of us were.)
But Erik twice? In a word: rerun. BB may have the WWE scriptwriter on board (seriously), but EPMB has brought over the seven-season rule: after that much time, any storyline can be recycled because the bulk of the audience will have cycled out and sent in replacements.
Are we now the reality TV equivalent of a smart mark?
It's not a reassuring question.