First of all the word geek means
A geek is a slang word for a computer expert, someone who loves computers or someone who is socially or physically awkward. (noun)
- An example of a geek is a person who has fun spending his entire day figuring out how computers work.
- An example of a geek is a person who has a genius IQ but is very uncomfortable in social settings.
Slang, multiple meanings and polarity of antonym
So, there are two meanings that you can use to look for antonyms and also the word geek is marked as slang, although I would rather call it informal, since it got accepted by geeks and non-geeks, so it is not really limited to any group (though the connotations of a meaning do vary depending on, primarily technological level of the one who uses the word; example - a geek for a stereotypical full-time beach surfer and for a stereotypical computer graphic designer refer to different people). I believe that you should also take that into account when looking for an antonym.
Also, if you say that you disqualify n00b, which I think is a quite fitting antonym for geek (both geek and noob might or might not be considered derogatory!) it means that you are not interested in an antonym of a completely different polarity, but something along the meaning of: regular user, average user, normal user, everyday user rather than amateur, inexpert, unknowledgeable, unskilled, untrained (which are antonyms of expert, the first meaning).
Maybe you would want to clarify if you mean average user or you are looking for a synonym of noob, but with no derogatory connotations?