2/ did the pilot not assess the local weather conditions himself prior to taking off?
I think the report makes clear that he did, and that the problem encountered with low cloud was associated with the return to land, not the departure from the zone.
This is a particularly worrying incident and procedural lessons need to be learnt from it and incorporated into MATS Part 1 as clarification. MATS Part 1 places restrictions on met conditions for the
issue of a SFVR clearance. It does not require
cancellation of the clearance under any circumstances and it is not a requirement on the pilot to maintain a particular in flight visibility. If the pilot's recollection of this incident is accurate, ATC may have inadvertently endangered the flight for reasons that were not obvious to the controller at the time, and there is an opportunity to avoid reccurence.