I think the bigger concern with clumping cat litter is with kittens. While learning to use the litter box they will sometimes play in it, roll around, and even eat some. Therefore that would raise concern.
Once the cat's litter habits are well established then it would seem ok to introduce them as long as it is monitored. When I picked up Nakita, my breeder suggested not to introduce her to clumping cat litter until she was older.