I signed up for beta on the Archive back when it first was formed, and donated money to help start it up (I observed the LJ fiascos in the HP fandoms, saw some writers I liked get banned for fuzzy reasons). Though to be honest I haven't been as active on it as I should, and went a long time without looking at it at all. I have posted to it recently, though, as part of refamiliarizing myself with it and looking at how far its come.
There's no gender identification question on the registration, nor any restrictions to 'slash only' when you post a fic (you can identify if a fic is M/F, M/M, F/F, Gen, Multi, or Other, or not label it at all). You can pretty much post any sort of fic, but they do encourage tagging it appropriately if you've got mature or explict themes.
The opinion of one person (or even a small group of ppl) affiliated with the archive doesn't reflect the policy of the entire site. Every group/forum has its loonies/snobs/trolls, and someone on the archive who stated the archive is only for female-authored slash falls into one or more of those categories. If what you saw was ever a disclaimer on the site, it must have been smashed very quickly. The ToS is very gender and content neutral.
The ToS is here:
http://archiveofourown.org/tos
I'll definitely have to play with the new download feature when I'm not exhausted (I probably shouldn't be posting at all right now)