God knows what he would do if he gets into an F1 car.....
He got into one.
Although I feel they could let some better rookies from GP2(let alone, an unexperienced one...)
Your sentence makes no sense. Either he's a rookie, in which case he's inexperienced and deserves a shot, or he isn't, in which case he doesn't? Test-drivers are used by many teams as PR-machines, which completely defies their purpose: Improving the car. Alexander Wurz, Pedro de la Rosa and Luca Badoer are examples of real, efficient test-drivers. Perhaps past their prime, but have a wealth of experience and knowledge. They may be over 30, some with a rather long racing-career, but they deserve a test-driver's role far more than a snot-nosed GP2 driver gunning for the big thing - they
know, they don't earn their fame by doing burnouts at the BMW Pitpark.
I don't see why Yamamoto deserves that role any less than other drivers, apart from having already proven himself to be crap - he still has more experience than a GP2 driver and as such would be a better
test-driver. Now, we all know he's not going to be the main tester (Alonso'll do that, probably), but rather a roadshow slave - in which case, yes, a GP2 driver might be the better candidate. I still think Renault just need to get a regular, full-time, capable development-driver.
Or, as mipuumal suggested, Keiichi Tsuchiya would be the best roadshow driver imaginable.