Sorry but scheduled flying at SEN is not a long term viable business. It is pretty obvious that Stobart have made it part of the deal to sell but it does seem odd that WX would accept. Either way, I would expect it is on a a fixed term basis which means the second the fixed term ends the routes will have to be self sufficient which is not going to be possible (see BE at BOH). The unfortunate thing is that neighbouring airports who have a genuinely viable business are stunted from realising their full potential as a result of the shady deals these surplus airports operate under. The comparison of SEN to CVT is spot on.
The SSJ is conducting its steep approach verification next year. A software update and winglets are required which are in the process of being commissioned. WX just need to keep the SSJ busy until then but the sugestion that operating them from SEN has been made on merit alone is laughable.