In reply to:

What I was *trying to say is that I don't see is calling a life vest a mae west as an example of antonomasia.

the term is new to me, but my inclination would be that "Mae West" could be considered a member of the class of "individuals or things which are or appear to be top heavy", in which case the term could be arguably be correctly applied, no? *must the most obvious class to which the personal name would be attributed be the *only class to which it can be antonomastically associated?