Wow, the UMC is actually making a stand. With all the social justice stuff that place has been pushing lately I am very surprised.
First off, having one's own mother or father administer a legally binding vow of marriage is kind of sketchy in itself, given the power of parental pressure.
Second, admonishment in the name of the Lord is love. Love is not always granting every wish, especially ones that give into sin... and before people start bellyaching about "love," same-sex attraction and opposite-sex attraction are not equivalent. Even the pride groups know it (see the joke "asking who's the man in a lesbian couple is like asking which chopstick is the fork"), except when they want to force the SSM agenda. While, thanks to Anthony Kennedy and his ilk on the Supreme Court, we are no longer able to outlaw the dangerous act of sodomy, it is still a sin, and allowing two men to marry is enabling it. (Why is it dangerous? Disease, mainly-- the act of sodomy injects bodily fluids into the intestines and breaks blood vessels.) I know most fathers are eager to see their son marry and be happy, but to settle for a same-sex abomination is a perversion of God's love.