"Canon" is not an issue here because it does not exist. (T:CANON)
I can't say much for the stage play's validity as a story, but if it was licensed in its 2005 incarnation, it likely merits inclusion as a page, though it would have to be about the 2005 production specifically, as that is the only licensed one.
Even if this play is deemed properly valid—and I can't think of any stage plays we currently deem valid—the 1993 performance most definitely would not be.
Now, I'm just going to guess that no stage plays have ever been deemed valid because they're not going to be exactly the same every night, and they also cannot be revisited. In this case, there was only one performance, which at this point was 11 years ago, and at best all we'd have to go on are some secondary recordings of the show, if those exist at all.
Are you actually suggesting that this stage play should be reconsidered as a valid source, or are we just talking about coverage?