Well I read the scenario as the light aircraft having departed so the runway was clear, but the Ryanair flight hadn't been given a landing clearance for whatever reason. Presumably the RYR crew got to whatever minima they would use as the decision point, then with no landing clearance (due to blocked frequency or whatever) carried out a missed approach.
Now I wasn't there, but it sounds like the RYR crew acted absolutely correctly in flying the missed approach instead of landing without a clearance. Although I would be one of the last people to defend Ryanair top management (for all number of reasons), I've never found the flight crews anything less than completely professional, and helpful when asked.
As other posters have pointed out, if they'd landed without clearance there'd be all sorts of muck flying now...