It certainly seems odd that the CGN management encouraged a CGN-SEN route while being in the final stages (presumably) of negotiations for Ryanair to set up a base at CGN. The proposed route network must surely have been discussed.
I don't see it as damaging to the Flybe/Stobart Air operation, it having caused a sensible but annoying change of plan well before operations commence, as there are probably other substitute destinations which didn't quite make it to the final six.