That seems far too vague a connection. And to what end? Just to favor the immediately previous episode over earlier ones? Why is that even a thing to aspire to? The point is to remind viewers of plot points they may have forgotten or fill them in on relevant events from episodes they may have missed. I don't see how "We've explored a similar theme before" is something viewers need to be reminded/informed of, unless they're doing a critical analysis or something.
It's not a matter of favoritism in my perspective. The last episode gave a little development to the Spirit Riders (a good thing) and their relationship with Irisa because they're the same species. I got the impression there's some potential for them to develop into a group that is a valuable ally to Defiance and not just token bikers, and that's kind of hard when one of your members is holding a vendetta against all humans for the actions of a few.
This week's episode has a similar theme, in that it's about Nolan and Datak having to work together regardless of their differences, and that ultimately everyone is going to have to learn to live with each other.
If the goal of the recaps is inform viewers of how the story's progressing (I agree with you it should), I feel this is how they should do it. Not just use some random clips from a few episodes ago because they happen to feature a character who's not necessarily a main focus. As I've said, perhaps it's just nitpicky, but if I'd missed the previous episodes and watched this one first, I wouldn't have gotten anything useful from the teaser because Ulysses isn't the point of the episode. I'd be left wondering why that teaser was shown and not something from an ep I got to catch up on later. * shrugs * That's just me.