The -ist suffix can mean several things in English. There's the sense of "practitioner of [an art or science, or the use of a tool]" (dentist, cellist). There's "[habitual?] perpetrator of" or "participant in [an act]" (duelist, arsonist). And then there's "adherent of [an ideology, doctrine, or teacher]" (theist, Marxist). Seems to me that the problem has to do with equivocation between these senses as much as with the lack of an "aspiring". And personally, I'm a lot more comfortable with the first sense than the others; you can after all be a bad dentist.

Perhaps we should distinguish between rationaledores and rationalistas? Spanglish, but you get the picture.