A risk maybe but I can only go of my experience, the leleupi will need there own territory usually around a shell or cave especially as they pair up. Obliviously I don't drop shells right in front of said territory and try to encourage the shellies to invade the leleupi's space.
The leleupi seem to be way more agressive towards each other and towards Julidochromis than the shellies which really don't seem to bother them, staying by there shells and doing there own thing.
I would expect the leleupi to prey on the shellie fry which is why I remove shells that have fry in them and have heaps of shellies of various ages and sizes .