Homosexuals--sodomists--are not a "class" of people. They are individuals engaging in immoral--and until recently, illegal, activity. Unlawful discrimination, in the sense of the 14th, is to prefer or prejudice on the basis of their intrinsic condition, not behavioral preferences.
No, the Constitution does not enumerate protections, explicit or implicit, to the homosexual act.
Actually, the 14th Amendment says "No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws."
I'm sorry, but I don't see anything about intrinsic condition. I see that all citizens are guaranteed due process and equal protection. What am I missing? ALL CITIZENS. Is that not clear to you?