I’ve flown a couple of Tiger Moths with slats and three without. Four of them had a tail skid and no brakes, one of them had a tail wheel and brakes. One had hand holds built into the wingtips, the others didn’t, some had different exhausts, I think one had the straps on the oil tank and the others didn’t. Whatever. They were all different in one way or another. I found the slats to be of no great value and preferred to have them locked all the time, mainly so I wouldn’t forget to lock them prior to aeros. I found the Tiger Moth to be incredibly benign in all flight regimes. That said, I don’t dispute they may be useful in extreme edge of the envelope cases or with brand new ham-fisted students, but I always liked to stay away from the envelope’s edges and never had the pleasure of instructing on anything, let alone a Tiger Moth.
All in all, I don’t find a story about a freak misrigging incident to be adequate reason to suggest that all Tigers should have operational slats.