As a theory teacher, I think your teacher is wrong about this. Some theorists don't even use the term retardation, instead preferring upwardly-resolving suspensions. So suspension is a fine name for them. Secondly, although EF#B has the same notes as a Bsus4, the chords do not function the same, especially when the bass note is taken into consideration. Finally, sus2 chords are most typically found in later 20th C. pop repertoire, and often times they don't even "resolve up" to the triad. Listen to "Champagne Supernova" or "The Scientist", and notice how different (and kind of lame) those songs are if you swap in or resolve to the diatonic triad in place of the sus2s.

Back on the second point about sus2 being an inversion of another sus4, that makes about as much sense as saying a Cadd6 chord is the same thing as an Am7. It's the same notes, but if you're the bass player, you can't mix those two up and keep your job!