(although what help cruising around in the sunshine VFR is, is anyone's guess).
Flying a C210 around the bush for 1500 hours has absolutely nothing to do with operating a commercial jet in airline operations.
These are misrepresentations of the amount and type of experience a GA pilot would normally accrue before even being considered for an interview with Jetstar et al.
I do not know of any 1500 hr C210 pilots who have been employed as 737/320 pilots. To the best of my knowledge, the majority are hired from regional multi-crew turboprops – with the odd one getting in with significant multi-piston IFR time. With a growing FIFO sector, some also have jet time. This type of experience is very valuable indeed.
To prove the relevance of this experience you just have to look at turbo-prop Captains who have successfully moved straight to the left seat of a commercial jet. ALL of the experience that they were able to draw from was GA.
Cadetships have their place, but if given the choice I do believe that a quality candidate with experience is better than a quality candidate without. Granted not ALL GA pilots are suitable – but a great number of them are.