Sure it's disordered. Any sin is disordered. Extramarital intercourse is disordered in fewer ways than sodomy, but it's still disordered.
Sinful and disordered to me are different concepts. Sin is a religious concept that does not exist for the non-religious who would probably define religious sin in the context of moral (or immoral) or ethical (or unethical) behavior. I think disordered is a good term to describe acts or behaviors that have negative consequences and, while perhaps accepted by society, nevertheless are contrary to what might be best for society.
According to dictionary.com:
Disordered: suffering from or afflicted with a physical or mental disorder.
The sexual act between a man and a woman is not intrinsically disordered. It was ordained by God for procreation. It's use outside of marriage does not in any way confer disorder on the act per se, since retains its life giving power.
The sin arising as a result of extramarital relations is particular to the perpetrator(s). It is their behavior which is "disordered", not the act.
Sodomy is intrinsically disordered by its very nature.