Problem with setting rotation of bones

Without looking extremely closely at your scene in Maya, the exported glTF, and the JSON, it’s hard to guess why this isn’t working or even whether it’s a safe approach. For example, the exporter may be making changes to the bones at export, so that they’re no longer ordered like they were in Maya. I’m not confident we can help you with that direction.

If you’re just trying to reach a pose, could you export that as a single-frame animation and apply it immediately rather than playing the animation? That sounds more robust to me; see discussion of animation workflows here: Gltf: Complex animation workflow?