What I do find interesting is that the captain was charged and the co-pilot wasn't.
How about the ATCo? He's just as liable according to: [quote](2) Every person commits an offence who—
(a) causes or
permits any aircraft, aeronautical product, or aviation related service
to be operated, maintained, or serviced; or
(b) causes or permits any other act to be done in respect of any aircraft, aeronautical product, or aviation related service,—
in a manner which causes unnecessary danger to any other person or to any property.
However I agree with Surplus1 about the responsibility of the authorities to set clear limits regarding the need for sufficient time to return under VFR.