Overall, it's a simple question that I don't know the answer to: Has anybody used him prominently in the last decade? If not, and if it's not registered (uspto.gov), then you probably OK. Remember, a trademark is pretty much like a brand name. If someone looks at your product and says, "oh, that's probably put out by (insert trademark holder's name)," then you're in trouble.
That said, I'm a programmer, not a lawyer. If there's money at stake, pay someone who gives this advice for a living and is liable for any loss you might incur through malpractice.
