How do you know that?
Sodomy is an evil. We can know this with certainty through unaided reason since it is an unnatural act. It is an especially evil unnatural act since it is an abuse of one of man's greatest powers, the power to procreate.
Therefore, those who participate in the act harm themselves. Since they are also members of society, they harm society, just as a single broken egg damages a dozen eggs.
The question arises as to whether all vices should be criminalized. One consideration regarding the criminalization of a vice is whether the suppression of the vice results in greater vice (i.e., the corruption of law enforcement). Another consideration is the gravity of the crime. This consideration can overide the former.
Such is certainly the case regarding sodomy. This crime strikes at the heart of society, since without procreation society itself ceases to exist.
Even among heterosexuals? Even as part of a more general procreative regime?
Since they are also members of society, they harm society, just as a single broken egg damages a dozen eggs.
How so? Nobody in a society has a duty to procreate. Do you propose requiring everyone to have X number of children during their lifetime?
Such is certainly the case regarding sodomy. This crime strikes at the heart of society, since without procreation society itself ceases to exist.
If an individual chooses no to procreate, that is no business of society.