The reason for my reaction and others is the possibility for future damage this decision poses. Like Justice Thomas, I think the Texas law was stupid and I don't mourn its passing.
The problem is the reasoning of the decision directly suggests that any state legislation regarding sexual morality is unconstitutional and implies that laws limiting marriage to one man and one woman would also be unconstitutional.
The problem is substantive due process. When a court finds a substantive "liberty" interest, as distinct from procedural due process guaranteeing procedural rights before one may be deprived of liberty, the door is opened for unlimited Supreme Court legislating. Why? Because there is no definition of "liberty" in the Constitution, so it means what five Justices say it means. It is almost an unlimited mandate to strike down legislation the Supremes don't like.
This was the fear with Roe v. Wade, another substantive due process decision. Over the years, the Rehnquist Court had pretty well restricted Roe to abortion, declining to interpret it as a broad mandate. I fear this decision wrecks that work and opens the door to lower courts throwing out all kinds of state laws.