They made a big song and dance about Denmark removing its aviation tax, so this finally sees them bringing a promised new route.
Wouldn't have expected a base at MAD straight away, but FR do seem to have a few Iberian routes from Ireland (and CRL) which they don't do from the UK (also AGP, FAO).
MAD just doesn't seem to be Ryanair's "type" of airport, but do they have plenty of spare space after the new terminal opened? Or are they operating these routes because they can get decent yields due to relative lack of competition?
Either way, just goes to show that FR will go anywhere if the deal is right.