I logged the jet ride, and the instructor endorsed the entry as well as my HA/HP endorsements. I don't see what the big problem is. If I get asked about it during an airline interview, I'm going to be honest and tell them it was a introduction to jet aircraft flying and was focused on how flying the jet relates to flying the Seminole and some of the differences in how the aircraft are setup. I'll be totally honest in telling them I don't remember much about the systems because I didn't have to learn everything about the systems.
The best way to go into an interview is be yourself and be honest. Do you really think they expect you to know everything about the Citation from a 3 hr "fun" flight? If thats what they expect, I'll go work for some other airline because its ridiculous. Take it for what it is guys, a really sweet opportunity to fly a jet after all the hard work you put in to make it through ATP. Kind of like a reward and motivator for those that get to that point. After that, you'll only be a few months away from an RJ job thanks to ATP.