I believe that rule was not absolute in the case of the Europa, Drachenfels, Oceania and Siege.
Those shards were considered special cases, on grounds of time zones, latency or special rulesets.
I think the way to go about it would be to contact Mesanna, and ask politely whether the Siege EM position is open, because you would be interested in applying.
As a side note, you may also want to not make a big deal about applying, because the EMs are supposed to be anonymous, and if you are talking about applying, and then Siege gets an EM, a lot of people will make assumptions.