I was thinking the same thing. First off, whenever someone says "trust me," as a rule of thumb, don't. His advice sounds really self-serving. Trustworthy people are always open to committing in writing or in ways that don't require so much trust.

Now, the dude who wrote the cover letter doesn't seem all that stupid to me. Sure, the writing isn't great, but for all you know English is his second language. I'm not so sure about his hacking skills, though (CSS?). I'd still interview him.