GREAT JOB Flowerpower!!
I suppose Alec could have gone to Exile by himself and Jon is occluded in the walk in photos and during the hugging of Alec on his return Jon got out of place with Reed.
In the 1-on-1 Duels the Lower went to Exile Island the Winner chose someone to go with them from the Winner's Tribe.
Note: Parvati asked Jeff if the Winner could send themselves. Jeff says yes but Jeremy assumed it had to be someone else and picked Keith before Jeff said you could choose yourself so Jeff never bothered explaining this option in subsequent duels.
Historically, in EI seasons often the person sitting out of the challenge had to go to EI but we know Missy did not go to EI.
Also, the Reward Winning Tribe, Team, or Individual would often chose someone to go to EI. So maybe the Yellow Team (Reed, Jeremy, Keith, Wes, Natalie) chose someone probably Jon to go to EI. And then maybe that person had to choose One person from their team to go with them and he chose Alec? Baylor, Jaclyn, and Josh have already gone to EI.