Probably because the one you posted comes up first maybe? Dunnooo~
I think if the users have something St. Patrick's Day related (contest/raffle thread, etc...), they can promote that on their own and link to Mene's site or social networks. Just have to be careful about setting any expectation about an official event if one hasn't been announced.
Obviously if any of the official Mene accounts posts something, people are free to share that and spread the word.