Leon you're living in cuckoo land..
What one is trying to get across is you might sack somebody, but do not expect that person having been sacked and having been debrainwashed and now happily working for a living to suddenly drop everything and turf up bright and breezy willing to jump through hoops for an Airforce that 2 years ago said b*gger off....l will never happen, all you will get is a resentful Reservist willing to do the absolute minimum or less to get through, after all it is not exactly doing anything promotion or job prospects wise for them, far from it, it is having the opposite effect on their civilian job. If you leave at the end of your service then fair do's, but sacked, you shouldn't have to do a reserve in my opinion as your service and your contract was terminated period.