Remember it's only a 3 aircraft base @ BHX (to start with) which means spreading said aircraft very thinly to serve both BHX and EMA as well as serving destinations on a very low frequency basis. In addition, W patterns are notorious for racking up delays, hardly what EasyJet would want to be known for when opening a brand new base.
There's no reason why easyJet can't successfully serve both BHX and EMA but with 2 separate bases like Jet2 and Ryanair who happily operate from both.
Me thinks this rumour has come from the same source that claimed Qatar were going to fly to EMA instead of returning to BHX.....