Not4u saidIt's this type of assholery on the part of people with agendas that turn reasonable people off. They know the Catholic Church's stand on marriage yet they chose to buy a plot in a Catholic cemetery and then slap the Church in the face by proposing a tombstone celebrating Supreme Court's decision on gay marriage and then feign indignation when the design is rejected. Fuck 'em they could have bought a plot in any secular cemetery. They're just looking for notoriety.
I do appreciate the validity of the point you are making in your initial sentence as well as the limits of its validity. The most important response is "Galileo Galilei" and "Copernicus". The Church was wrong there initially, too; knew it was wrong for 400 years and 200 years respectively; and only in 1992 did the Pope issue a "mea culpa" for the Church's role.
The Church is wrong about homosexuality, and therefore, since these two are Catholics—their church is wrong-headed and in error—they have as much right as any other Catholic to ask to be buried in a Catholic cemetery, and perhaps with a bit more moral authority than the Church's, since the Church does deserve the slap in the face, given the Church's teaching is wrong.