That's a tough call to make. I would say NO, because unless the guy can provide proof (i.e. the physical CD or cassette) he may be lying to you and if you then make a Vogoned version of this song based just on his word, there could be legal implications. What you could do is ask him to send you the CD and then you could Vogone it from there. That I believe, would be legal.
MTU also has a legal issues section, which might be of some help also:
http://www.mtu.com/support/copyright-notes.htm
Hope this helps.
PS feel free to correct me if I'm wrong ;)