Roe is emphatically not irrelevant to the sodomy case. If the court rules the sodomy statute is unconstitutional, it will almost certainly do so on the basis of the "right of privacy" created in Roe vs Wade.
Roe purports to find a penumbra of emanations of privacy rights somewhere in the bill of rights. Those privacy rights include the right to abort a child, anywhere anytime, according to the Supreme Court.
The bill of rights (containing that supposed right of privacy) only applies to the States thru the 14th amendment (so you are right about the 14th amendment). My recollection is that the right of privacy based on ROE was the issue before the supreme court the first time the court dealt with the Sodomy rights issue.
So you have to have Roe PLUS the fourteenth amendment for the US Constitution to prohibit state sodomy laws. (If sodomy were not permitted to homosexuals but was permitted to heteros, then you might have an equal protection argument, but I don't think that is an issue in this case.)
If you think ROE vs WADE was good constitutional law, then you will love the Constitutional Right of Sodomy. If you don't like ROE, don't let libertarian tendencies push you into supporting a very, very, bad constitutional result. This decision would be a continuation of the huge increase in the power of the federal government that was started by Roe vs Wade--that is, the power to tell all states what morality they can and cannot, must and must not enforce.