USB Connector not following USB Protocol
Using usb connectors in a non-Standard acceptable method is against the USB specifications. Unless you are looking to conform to the USB specifications, there is no technical problem aside from end user problems. Non-standard usb connectors are fairly common, as is non-standard combinations (Usb female A to Usb Female A is common but against specifications, as are USB Y-Cables used to power external harddrives).

The only thing you can't do, according to the USB forum, is have the usb logo or name.