I spent a lot of time thinking about that, but, in the end, I don't think anyone could justify the words "bulletproof" and "ssl" next to each other. So that was that. The "SSL" part was in the title chiefly because, colloquially, that's what everyone uses, especially for certificates.
On a positive note, I was able to add "PKI" to the title, which makes sense because the book is actually about PKI as much as it is about TLS. A win-win, I think.