One act is ordered to pleasing one's spouse, the other is orderd to pleasing a member of the same sex. The latter is unnatural.
Fellatio:
Between man and woman is OK, but between man and man is Not OK.
See above. However, "finishing" the act orally is unnatural.
Anal Intercourse:
Between man and woman is OK, but between man and man is Not OK.
Unnatural in both cases.
Where is the “equal protection under the law?”
Homosexuality is unnatural and intrinsically disordered. Heterosexuality is natural.
That's your opinion, not the opinion of the Supreme Court.
Furthermore, I would suggest to you that many Christians consider cunnilingus between married people "unnatural."
Therefore, your opinion that cunnilingus is not unnatural under certain conditions differ from the Christian position through centuries.
Before long, these scholastical distinctions are going to end in the conclusion that the use of clockwise tongue strokes is acceptable, but that the use of anticlockwise tongue strokes is unnatural (or vice versa in the Southern Hemisphere).
As are liver transplants and human flight.
Are you against those as well?