It's because you're JFK based vs. CVG based. If CVG based, they have to fly you home as a lineholder with more than 48 hours in base. If you switched, you'd be bidding #3 in CVG vs. getting nothing but CVG reserve lines as a senior JFK FO. This is the only way your seniority works for you. As a JFK guy bidding CVG lines, you're essentially junior to every CVG FO. On the plus side, your seat lock expires soon.