> As I understand there is lot more tooling, standards & existing software examples around JSON for project & records management

I don't understand why that is relevant; as long as there is a minimum level of tooling, libraries and support for their choice, what benefit would JSON bring over XML? I don't see a clear reason for one over the other.

Honestly, I'd have the same question if they chose JSON and someone asked why did they choose JSON over XML - Why wouldn't they?