I think the main issue is the time needed to get the experience required for the upgrades, not the check flight itself. If he doesn't hold the experience required for the RPL, then he has to gain it all before applying for a higher grade of FIR. Even if CASA grants a licence or rating you then have to pass a prof check done to at least the level you intend to use before you can wield the privileges. So even if CASA had granted the licences and ratings he would still have 'hoops' to jump through before exercising those privileges.

My closest friend is a 37 yr (69 y/o)
16000+ hr Ga trained flight instructor. He makes the majority of his living out of teaching poor performers from the local Division 1 university flight school how to fly.
My upper-level instructors all taught in WW2 or Korea. He’s kinda the same way.
Not a lot of fails with his students regardless of jerk Designated Examiners…
Flying in the military, and learning to fly an airplane are different. I suspect that the reason Colorado Springs is infested with 172s has something to do with this. (I further suspect that the reason that the USAF wrecks a few planes could be reduced by flying a trainer that will bite when stalled…)

I gotta go with CASA. The USAF for a time had instructors that came off careers flying B-52s and such wrecking Slingsby Fireflies (T-67s) because they had no clue how to deal with just one engine instead of eight and the Firefly was not as forgiving a plane as the old T-41s they replaced.
Also as I learned teaching at a military associated club, flight instruction and military flight instruction are very different things. I got in trouble for being "too nice". Not that I let anyone slide with bad flying, but I wasn't yelling at them like some bad recreation of a drill sergeant. (cue scene from An Officer And A Gentleman). I was like "My students pay my bills, if I yell at them they will find another school or another hobby and I won't eat".
* while the Air Force rethought their training, new students got a check for civilian flight schools and they got more pilots for less money than ever before LOL

How much yelling have you observed RAAF instructors doing, in either military or civilian training? (There is, of course, the notorious 'Screaming Skull', but he wasn't screaming in the capacity of an instructor.)

First heard this story during flight training 1967 and thought it unlikely, came across the videos a few years ago and it forced a smile.

I don't know about military instructors, but I've known several civilian instructors that yell and carry on berating students, as well as those that physically hit students with folders and other items at hand. I'm sure a few military instructors may have had anger issues, as do many civilian ones, there's no place in an airplane for dramatics and carry on.