It's a fine tool for the job, but it sounds like their IT are being lazy.
A PCI compliant environment has to have everything audited and documented. Auditing has to be done every quarter and documentation has to be reviewed every 6 months. In other words, it's a lot of work. It doesn't matter what OS is used, it takes a lot of time and effort. So in order to implement Windows 10 (or anything else for that matter), services have to be audited, permissions documented, any GPO changes must be documented and audited.
If that's the environment, they're probably waiting for Windows 10 to either become a business requirement or they're waiting for their next audit/documentation review period.