Yes, you make good points.
I'd probably drop the 5000 hours in favour of strict training and assessment criteria (your "clear demonstration of skill".) I think 1000 of the right hours is more beneficial than 5000 arbitary hours (after all, look at the chaps who get to skoot around in the RAAF's F18s, not much hours, but very good training.)
The New Zealand Warbirds Association certainly has the experience available to give adequate training. Until the CAA step in, it comes down to whether Joe Bloggs has the ability to recognise his or her limitations, and seek the training.