I don't agree.
Everyone is equally free to engage in sex with a member of the opposite sex. Likewise, everyone is equally prohibited from engaging in sex with a member of the same sex.
It doesn't say only black people, or only men.. It's everyone, period. The law is universal. (as least the Texas law is worded in this fashion, your mileage may vary elsewhere.. )
Would you consider laws allowing bestiality with sheep but not with goats to be a 14th amendment violation?
Bias is not made more acceptable -- or constitutional -- by being universal. If this law did not single out homosexuals, it could be considered constitutional. But in creating an unequal class of offenders, it creates an inequity under the law, which is specifically forbidden under the Fourteenth Amendment.