That's fair. I figured you would have to do something C3 side that would be at the expense of performance to some extent because I've made stuff in Blender and didn't see a way gltf could store it.
It would probably still definitely be a useful feature if used appropriately. Like attaching objects with collision boxes to damage the player if a limb hits them or chain models together maybe.
Currently I'm using the plugin for giant bosses in my first person horror game and some other various things that only it can pull off. Otherwise enemies and stuff are like DOOM billboards. So pinned objects might work fine in that setting.
This is a great plugin though. I've been using this stuff since Construct 2 and I never thought we'd be having full 3D some day even if only cosmetic.