A Chinese citizen in China holds an unexpired short-term Schengen visa (although essentially unusable at the moment) and wishes to travel to Switzerland for an exceptional reason. After a semi-refusal from the embassy for the exception, he has received an exceptional entry authorization from the State Secretariat for Migration in an letter, which they can confirm to suffice for the border authority. It is unclear if this will be accepted by other Schengen border authorities (e.g. Germany) for transit purpose, but I believe it is unlikely.
However, I am wondering if the passenger will be allowed by the airlines (particularly SWISS) to board a direct flight to Switzerland with the letter and the old visa.