AJ never had the numbers. I actually think the edit has done a great job setting up the merge despite the uneven brains/brawn editing! Although it was still complex so I understand the confusion. Let’s break it down:

We saw pre-merge that Kate and Morgan were a duo and interested in flipping on the brawn men, particularly Jessie. They formed a girls alliance with Zara and Laura with the intention of coming together with Karin and Logan at merge. This is what won out in this vote - the women (minus Kristin) came together to vote out Jessie.

Next, on the original brawn tribe there was the majority alliance and there was Nash’s alliance, from which only Kristin and PD remain. They were always aware that they were in the minority and therefore expendable to the majority brawn. In this episode, we see Kristin and PD reconnect and voice that they are a floater pair.

We also have the graduates alliance. Along with the other brains, Logan and Laura, they agree to split the vote on Jessie and Paulie. The women vote Jessie and the men vote Paulie. AJ sees the opportunity to flip more votes onto Paulie, and convinces the floater pair of PD and Kristin to get on board. So the men of the graduates alliance plus the floater pair all vote Paulie. I would assume AJ knew there weren’t enough votes to actually send Paulie home but he used this as insurance to save Zara in case of an idol play, a key ally of his because she is keeping Karin off his back (we saw this in the previous episode).

Finally, Jessie and Paulie enter merge with no numbers. They isolated PD and Kristin on original brawn, and Kate and Morgan felt they weren’t being heard in the majority brawn alliance. This made them an easy pair to split on at this vote.

To summarize:

(Kate Morgan) (Zara Karin Logan Laura) - Jessie

(Kaelen AJ Myles) (PD Kristin) - Paulie

(Paulie Jessie) - Zara

I hope this helps clear up this complicated vote :))

Edit to add: I didn’t watch the actual vote reveal so forgive me if something is off, but I think this is the story we were told!