The ruling made no claim of 'normal' as you claimed.<quoted text>
"The petitioners [Lawrence and Garner] are entitled to respect for their private lives. The State CANNOT DEMEAN THEIR EXISTENCE OR CONTROL THEIR DESTINY by making their private sexual conduct a crime." (Justice Anthony Kennedy, Lawrence v. Texas).
Sounds like he was saying that homosexual behavior cannot be considered a crime. And if it's not a crime and heterosexual behavior is not a crime, then they must be equally legal under the law.
The ruling was based on private behavior and self-incrimination. If the law made the determination you claim, it would conflict with scientific fact that sodomy obviously is harmful, unhealthy and demeaning.
Nor can you claim that sodomy is 'equally' legal under the law. It can only be legal by the avoidance of exposing the inherent harm, unhealthiness and demeaning nature of sodomy. Natural sex has no such hindrance.