echo victor 

I'm no expert, but I remember reading a rumor that the wide, hammered rivets on Brooks saddles started out with a company that would drill out the original rivets, make some changes, and then needed a larger rivet to replace the originals. Maybe you could try something similar to salvage this saddle - drill out that rivet, cut some of the leather in that location, maybe punch a small hole or something at the edge of the existing crack so it doesn't spread further, then re-rivet with a larger headed rivet?