I had heard of this rumour a couple of weeks ago. Certainly there is a demand for Scandinavian destinations from LTN as none are served at present. At one point, it was thought that Ryanair would establish a daily Stockholm Skat(also run by TBI) but nothing has materialised as yet.
Duo at Luton would serve a niche market and one that would probably work quite wel l - large business market a couple of junctions up the M1 at MK plus local catchment area. Somehow though, I can't quite see it happening.