I recall reading a thread on this forum about this, recently, although I can't find it any more.
From what I remember, your friend is right, so long as his Class 1 license says something along the lines of "This document may also be used for exercising those privileges which require a Class 2 medical" or something like that. As long as it says that, he can use it as if it were a Class 2 license, with all the same revalidation requirements. But if it doesn't say that, it needs to be renewed every year.
FFF
--------------