Many older dickish commuters didn't bother listing for any seat until last minute and would then only list for the JS because they knew they were senior enough to get it. That forced junior guys to compete for a seat in the cabin against the gen pop rather than the senior guy easily getting a seat in back and leaving the jumpseat for junior commuter.

I'd guess he was just trying to ease your mind that you weren't getting bumped off jumpseat by him, regardless of delivery.