Well, there were also a lot of Greeks in New Orleans who founded the church there.
Of course, but they catered mostly to Greeks. Russians converted Alaskan natives and appealed to a broader base of home-grown Americans. Also, because of the same liturgical (Slavonic) language, it was easy to incorporate other lavic Orthodox. If I had to choose between Slavonic and Greek, I would choose Slavonic because that's the languge I understand. And Greek is a linguistic monad.