Does the long answer revolve around the difference of a media profile vs an ICC profile and how one can be used and the other cannot?
I was starting to type all that but then realized you probably said short answer for a reason.
Yes, So media profiles and icc profiles are different. I suppose you already know that. For those who don't, an ICC profile is the file that will match your RGB colours from your computer to CMYK process colours to the printer.
A media profile is a file (different extensions for different programs) is your ink restrictions, linearisations, ink limits, ink drop sizes & curves, ICC profile and what ever else your RIP's colour managing system can handle all in one file.
The reason why you cannot use a newer media profile on an older software is because the older software will have less features and wont understand the newer features & tweaks. And sometimes companies do this so you have to keep your software up to date. (Which i don't see it as a bad thing personally as i like my software up to date.)
You can export your ICC profile from the media profile and use it in a legacy version (7 in the OPs case) But that requires your ink restrictions and everything else to be identical to the original media profile. But even if you do make it identical, the software might understand it differently and you still won't have the same colour as the original.
IMO to much stuffing around. I personally would update to x12 or wait for 12.1 and get an extra printer licence to run both printers though 1 RIP. Or just get another licence for x10.