I am a norske Lutheran. My grandfather was a Lutheran minister and a missionary in China. My father was a physician missionary as I have also been. Trust me. I know my Bible.
I’m glad you know your bible. I pray you’ll rely on it and not your liberal church as you definitely need a greater degree of spiritual maturity.
Christians burial is for Christians. Openly homosexual (I'm not talking about those that are struggling with same sex attraction), and are unrepentant by partaking in the sin, are not, by definition, Christian.
And denomination, or what what your family may have done under the guise of religion, doesn't change that.
The pastor was correct in his decision.