Repairing improperly installed flashing
Since the flashing is there and will trap water your choice is a good one or a Henery's or Black Jack roofing product will seal the edge so water doesn't get trapped. I would go with the least expensive since they will all last longer than the time your inspector said was left on the life of the roof. Not much water will go to the side but wind can push it under and then it is trapped.From what I see in the photo the roof looks to have quite a few years left.