I think the airframes are Irish registered so you need an EASA licence to fly them, after leaving that organisation any UK licence holder no longer has one so unsurprisingly SAS are not interested in hiring them.
The question really is whether a Scandinavian company, working through an Irish subsidiary using Irish registered aircraft , should be allowed to operate flights originating in the UK, my opinion is that they should not.
The UK government is asleep at the wheel, us usual.