There are no membership restrictions, so go level your guild!

EVERYONE can enjoy double status this weekend from Friday, September 5th, 2014 at 12:00 noon PDT, until Sunday, September 7th, 2014 at 11:59 PM PDT!

A footnote to the announcement clarifies:

This event doubles the base status earned by defeating encounters, or rewarded from quests. Guild status is rewarded from that base amount, so yes it is in effect doubled.