Like most things, this is not a black and white issue. Some show cave developments have been done sympathetically and well, some not. Some caves are clearly suitable for such development, some are certainly not. All these things should be looked at on a case by case basis. As far as this particular development is concerned, as the cave is an SSSI, consent had to be obtained from Natural England and I understand that they have people overseeing the work. I can only presume that the oversight is being done in a proper and professional manner.
Thing is, if someone against desecration of natural cave, I assume that they are against digging. Take all those bloody bits of wood and scaff out of the bottom of Eldon, bloody vandals!