No, seems like he just messed up - one tank completely empty & as a result of fiddling with the selectors he managed to introduce air into the fuel line from the other tank which had around 60l remaining. Slightly surprising as the pilot had > 10,000 hrs, albeit just 5 or 6 on this type.
It's not the first time something similar has happened with Partenavias in NZ, I seem to recall reading of a couple of instances where the fuel selectors were mis-handled which resulted in fuel being shut off completely. In the cases I can think of the fuel wasn't successfully returned and a forced landing resulted. None of these particular reports mentioned anything about stiff selectors but IIRC one did say something about the selector being slightly between detents which was an exacerbating, but not primary, factor in the resulting accident.
I've never flown one but it seems to me the fuel handling is something that should be underlined with these machines - whenever I read of a Partenavia issue it almost inevitably involves fuel issues in one form or another.