GBALU53 -
This sounds like a minor short-term issue to me. The ATR72 is perfectly adequate to fill the gap on a route such as BHX-BHD (on which the E195 flies) until the new aircraft is available. Range is not an issue and the flying time penalty is probably limited to around 10 minutes. The jet / prop flight-time differential is minor on most of FlyBe's network.
I'm not saying that BHX-BHD is necessarily amongst the routes directly affected - I don't know FlyBe's plan - but much of the airline's network matches the criteria of this example. It seems to me that FlyBe is acting responsibly towards its customers by leasing in capacity to make good the shortfall caused by the delivery delay. Some companies would not do this.