Ryanair billboards around Belfast are nothing new. As an example, when they were still flying from Belfast airport back in the day, billboards for flights from there were frequent sights around Derry.
Having said that. I'd love to see FR at BFS. They'd shaft the management to within an inch of their lives, pi$$ EZY off, and make an already grim airport even worse. I wonder would they insist upon some kind of update to the wooden signs that get hung at gates, giving the place the feel of a 1970s third world terminal? All's missing is the cigarette smoke and heat.