The E145 is on wet lease from City Airline, as the Eastern SB20 are all being utilised for the Scatsta run and other commitments, along with training of crew.
It is not a reversal in company model it is just that for the time being whilst IAC are covering the cost for Eastern to do the Scatsta run, after the sad demise of Flightline, until their official contract starts, Eastern have farmed out some of their work.
RL is not daft and it is probably saving him some money.