It has been pointed out by several people in the last couple of days that the scene is parodied very often in many, many venues.
Those parodies only very rarely bring any significant bad feelings from anyone.
The intents motivating those parodies will of course vary, and significantly so, but I don't think it is too much of a mistake to assume that in most cases the decisive factors will be the number of people in evidence and a vague perception that the moment portrayed will be consequential. There just aren't that many other well-known scenes that present about a dozen people and a perception of gravitas.
Speaking about myself, I certainly don't think much about Christianity or Jesus when I see a random parody of the Last Supper.
While typing this post I came to realize that, to me at least, it feels unlikely that a group of people would parody the scene with pejorative intent by using themselves as stand-ins for the Apostles.
For the perception of disrespect to exist, you have to start with a predisposition for perceiving either the reenactors themselves or their willingness to reenact the scene as somehow reprehensible. Otherwise it is just much more natural to see the reenactment as a respectful homage.
Christians themselves tend not to have too much issue with reenactments of moments described in the Bible, such as the Nativity, the Via Crucis, the Crucifixion itself. Those reenactments are often/usually very public and very much open to people who do not necessarily accept Christianity. And the Last Supper scene, while informed by the Bible, has a very significant element of Leonardo da Vinci's work as well. It is considerably less direct a reference to Christianity than those other reenactments.
So no, I don't believe that there was any sort of disrespect towards Christianity involved in the episode. The disconfort may well be genuine, but it is something for those bothered to consider and understand, and hopefully resolve as well.
It is probably not out of place to also point out that Christianity is usually presented as a creed that wants to reach out for all people, and there is no obvious reason why transgenders would be excluded.
I am all for protecting the rights of public blasphemy, make no mistake. But I am seeing none there, or even any attempt. Not by the reenactors, anyway.