I've been talking to colleagues working for DAS and it seems that this decision has come as a complete surprise; they had heard nothing until late Thursday night. Today has obviously been a hive of frenetic activity. They have been continuing to operate four aircraft up to this point and had (they thought) been working through issues successfully, with an end date of the end of this year. The airline has successfully relocated its maintenance base to Manston and has had a good audit by the UK CAA. Various other improvements were also in process. They are intent on continuing operation in whatever manner it is possible to achieve.
My information is that this issue appears to be driven largely by the inspection team at Amsterdam who appear to have taken a particular dislike to the airline.
It's true that the airline has had to reduce the number of aircraft operated, partially brought about by the bankruptcy of the lessor.