I think with things like this it's difficult to read it as a joke. Mainly because a whole variety of people, people in yuri centric communities and homophobes alike, are still trying to dismiss this couple. Often using the same reasons, so for example we're often having to say that the random homophobic Bandai Producer was not the final word about their marriage, and instead the actual series director got the last word in with saying they're married. Plus the show is clear about their marriage even with the restrictions the creative team faced.
I think it's something where people are very tired of having to defend this couple and other couples, I know I am at least. So even if it's a joke I do wish it's something that people didn't joke about.