I think it is advisable to watch what you wear as well. What you wore gives signals to the wrong people (except perhaps on a beach). The right people would just ignore it.

The only reason he drifted away (if that is what he really has done) was because too many people closer by were preoccupying him for his schemes.

I have read other true stories and this type do let slip things about their plans like this one did.

Would you feel safe enough giving his e-mail address to the police? (Would others please guide me here, e.g perhaps the evidence is too vague? Would he guess who gave them the tip off?)

I'm sure you're thankful to providence that there was something about you that was offputting to him at the time.