Not the federal government, however.

There are specific prohibitions on certain categories of state laws, like granting titles of nobility, creating non-gold/silver currencies, etc. The federal government cannot constitutionally regulate sex positions, because anything not explicitly covered in the Constitution is reserved to the states, or the people. In that broad grant, however, the states individually can make or avoid making law on any topic.

As others have mentioned, the Supreme Court has frequently worked around the Constitution for reasons that made sense to them at the time, including the original ruling that this one overturns.

>The federal government cannot constitutionally regulate sex positions, because anything not explicitly covered in the Constitution is reserved to the states, or the people.

That being said, there's probably not a constitutional way to enforce laws regulating sex positions. Even if you don't agree that such laws are clearly discriminatory in intent (let alone impact), the privacy violations necessary to prove guilt "Beyond a reasonable doubt" almost certainly violate the Fourth Amendment, and any theory of harm would implicitly (if not explicitly) rest on religion.

This is all assuming you don't accept Griswold as a reasonable constitutional argument that pretty obviously would extend to the kinds of sex people have.