So a Professor of Mathematics is not allowed to teach Primary school kids math? This is probably why Australia has terrible literacy rates, of course CASA (and our education department) would have them teach Art class while a graduate who didn't even do math at high school teaches math subjects to kids. I agree some highly educated people can be poor teachers because of personality traits, but that goes for those with low education as well. Pretty sure somebody that has a deeper understanding of a subject that also has the traits to be a good teacher is better than somebody who has very basic understanding of something....
If they are seeking RPL for the relevant experience so that they do not have to do the hours required in GA aircraft, or PMI course, I can't understand why not. That is if they still have to pass the test itself. If they are trying to get out of the test itself, I can see an issue and hurdle they will never get over.
Let them do the test, if they have what it takes they pass, done, move on and teach. Having a wide base of experience in GA is exactly what GA needs. CASA seems to prefer a method where toddlers are teaching babies to play concert piano...