I have some very serious concerns about even the thought that because an ATCO might have a PPL he/she could/would take it upon themselves to offer a pilot instruction on how to fly the aircraft!
Unless you get to instructor level and are able to maintain that level of competency then I suspect you might well do more harm than good (especially if you're not familiar with the aircraft type). And how far do you go? Single engine? Twin? Jet? Multi jet?
What do pilots think about this 'idea'?
My view, as someone who has handled dozens of 'emergencies' as an ATCO, is that the pilot should be sufficiently trained to fly solo before being let loose. ATC can (and do) help when they get lost or suffer other 'emergencies' but not to the extent of attempting to offer basic flying skills advice. I could easily imagine being sued for giving the wrong advice. Whereas I have no problem in contemplating any sort of prosecution for doing my professional job of controlling aircraft and giving assistance. I think assistance in flying the aircraft is WELL outside of the scope of ATC.
BD