With Jet2 not even into a full years operation at STN and the fact that it's the airlines only southern base why would they consider SEN seeing its only about 38 miles away and with limitations regarding it's runway not being suitable for Boeing 738's.
Someone is getting carried away with themselves regarding this 'so called new' airline coming to SEN, but I think DC3 Dave and his Flybe assumption may well turn out to be the case.