The FlyBe idea does make some sense.
Whatever routes Regional (owned by Granite) operate on their own account would be marketed by FlyBe. That gives FlyBe a slice of someone else's revenue for not doing much, and it gives Granite a better-known brand and distribution system, hopefully attracting more passengers than they would as a stand-alone. It also reduces the amount they need to spend on marketing, because there would be no need to expensively promote a new brand.
All FlyBe need to be careful about is clearly determining which routes can be flown by Granite/Regional and which by Loganair.