They have said its not supported since vista. Them idiots said logonscripts are not supported. So what? You still use kixtart? Even when it was included in reskit, there was a disclaimer of it being unsupported.
Microsoft support has always been a joke any ways and bears no meaning what so ever.
The point is not to ask for the non-existing support but to make the product we paid for work as promised in the first place.
Apparently it was still a problem in Windows 8.1 so I supposed it still applies to Windows 10.
Besides, I personally think this is exactly what is going on, and if this registry change fixes his problem then he knows where to look.