There is a fedora kernel mailing list which you might like to try asking on. To hazard a guess I would say that by the time each kernel has gone through updates-testing then a new release has been made - note that today
2.6.22.4 is out, thereby nullifying the point of keeping each version in updates-testing for the necessary period. If a flaw is severe enough to warrant an update then I think it just gets pushed to updates straight away.
It might help to understand where the above kernel you mention is located and why you want it...?
Cheers
Chris