The L3 & L4 service manual describes exactly what the N900 is - as do the other schematics and manuals. The people you show the N900 to are not going to read these, even if you keep copies handy everywhere you go...

Therefore, the appropriate answer is that you don't have to convince anyone of anything, and you shouldn't even try. You have nothing to prove, you know what the N900 is, if you like it great, if not, great. Let Nokia handle the rest.

Probably a better question to ask is why you feel the need to actively convince people your N900 doesn't fit some broken piece of marketing terminology anyway. : )