First, I am on an account with only level 1's. So, you'll want to change your requirements to take care of that.
Then you don't use that account to register for the forum, simple as that. It's no different than any other lv1 poster. As with the posters above, I'd be wondering why. All I can imagine is it's a mule account, in which case you should be using another account to post with.

1) only people with relics can make posts about relics; empys, magians, etc., same idea
2) only people with 99 Mnks can make posts about mnks, mnk gear, mnk abilities etc.
3) only people who are on the test server can make posts about the test server
On 1) and 2), people without those things have legitimately askable questions or topics to discuss. You don't need to be level 99 in a job to discuss that job in any way. You'd be wrong to claim yourself an expert, but what if you're new to a job and wanted to ask questions about it?
On #3 I can agree to the extent that only test server users should be able to post in the test server sections. However, if people want to ask questions about the test server elsewhere, that should be fine. They'd need a lot more moderators to police crap like that anyway.