While I'm against gay marriage, I will say that there may be some Orthodox with the opinion that while they oppose sexual immorality (including homosexuality) and oppose homosexual marriage in the Orthodox Church, they may not be in favor of banning homosexual marriage for everyone (including non-Orthodox). There was a time that I felt that way as well.
Tom Hanks acting in a movie doesn't mean a thing. Look at the Da Vinci Code series, and he has never endorsed it nor said it was true. In fact he's said the opposite, and that it was fiction, not to be taken as historical reality.
Things aren't always black and white. Someone could be for gay marriage and against sexual immorality. They could be against abortion, but pro-choice. They could be both Orthodox and believe in evolution. One doesn't necessarily exclude the other.
I have a best friend who is gay. If he gets married, I won't attend his wedding, but I don't feel right telling him he can't get married, even though in our state it wouldn't be recognized legally. I support him and hope he is happy, while at the same time I recognize that any sexual activity outside of marriage is wrong, and the only true marriage is between one man and one woman.
I have a relative who is a freemason, does that mean I reject him or tell him he's a part of an evil organization? Does he have a right to be a part of it? Yes he does, even if it isn't right.
Yes I know I'm bordering on politics here, but I feel that the discussion about Hanks' "Orthodoxy" inevitably would intersect with a degree of politics, since the issues of morality involve both faith and politics.