I guess so and that's also understandable, esp. with limited manpower. But maybe this is something also for freelancers to try to get into development to work on some older chips.
This is a great opportunity for people who actually have those cards to test and report the results. It shouldn't be hard to switch it on and off for different parts, people just need to report whether or not it works for them.
If there aren't enough people out there to do that, then there's a very strong argument to be made that it's not important enough to waste anyone's time from AMD on it anyway.