I like diving with a canister light in open water so I personally don’t see a need for this.
AMPLIFICATION: A can light increases my standoff, improves consumption and supports communication over greater distances. I can focus and inspect things further away and this saves the gas I’d spend otherwise swimming to get closer. The more powerful beam allows me to wander off on my own out of visual contact with other divers but still communicate with them light-to-light. The DM guides I dive with tell me my can light, a DR HP50 (that I acknowledge is rather the Hello Kitty or Betty Crocker Easy Bake Oven version of can lights), has way more punch and that inspires confidence in the DMs. They know I’ll periodically turn and ankle kick against the current until I see a bubble plume or two, exchange a smooth, controlled OK and then be on my way again.
Because I dive with a can light, I don’t need a kydex hose holster.
If I dive without a can light for some reason, I just form a relaxed bight with my LH and slip it under my waist belt. I pinch the outbound and inbound hose together where it passes under my waist belt to ensure tidy routing.
Attaching something else to the waist belt when there’s already a minimal-but-effective solution in place seems out of place in the “Hogarthian” subforum.