I really hope the high titres are just his body fighting it, as cats can fight it and it not develop into FIP, if you do some research there are 4 'effects' when they come into contact - they will fight it completely and then be immune, they will fight it but become a latent carrier (so it might flare up in old age), they can't fight it that well, so it turns into dry FIP (which can be quite slow), and they can't fight it at all, which turns into wet FIP (whihc is the worse). The mass doesn't look good though, have they taken a sample from it at all?