Creepy guy stalking my friend?

No, stay out of it, she needs to avoid him as much as possible, change her routine, etc and not say or write or have any contact with him at all. Anything she says, no matter how negative, he will see as a positive sign and use that, if she says NOTHING and ignores him, he will eventually get bored and move on. The more she explains and talks to him, the more she encourages him..."NO" is a complete sentence.