Hi James,
I haven't experienced that particular phenomenon of having a BP prefer a separate cage for eating, but good for you for figuring out a novel way to get him to eat. I have had BPs decide to stop eating, refuse every trick in the book, and then start eating once I change their location in the rack or moved them to a different rack altogether. Sometimes it's a change to a slighter smaller tub, a very slightly warmer or cooler one, or a different place/type of rack altogether (I have both Freedeom Breeders and Animal Plastics racks of different sizes.). Maybe there is something about that feeding cage that makes him more comfortable. I wonder what would happen if you just permanently moved his quarters?
Anyway, I'm glad he's eating for you!