I think it's a good idea - to me, it isn't immediately clear that you must earn the reputation exclusively through other people's votes on that site, given the original description alone (I can see that I have that much reputation - how is it not on this site?). I assume the reputation link goes to the general FAQ on reputation, which also doesn't address this particularity.
As an added bonus, it also introduces newer users to the association bonus (I didn't know that happened until it actually did, although that was a nice surprise).
That said, your suggested rewording made more sense before the edit. It should be something like:
You must have earned at least 10 reputation on this site (without an association bonus).
The link should still be there, but you must earn 10 reputation without the association bonus.