I have reported earlier on the action of MNL Capital against the 2015 Belgian Vulture Fund Act (my EN translation here), on which I have a paper here. I then reported on a related action (where MNL were joined by Yukos).
At the end of May the Belgian Constitutional Court, ruling 61/2018, rejected an MNL challenge to the Act, which was based inter alia on an alleged infringement of the Brussels I Recast Regulation: at A.23.2: MNL argued that Belgium cannot across the board reject vulture funds activities (I agree) based on an absolute ordre public argument against them: MNL suggested this entails a one-sided reading of ordre public in favour of foreign entities refusing to honour their debt.
Due in large part to the peculiarities of constitutional review in Belgium, the Court at B.15.4 looked at the argument purely from a non-discrimination point of view: creditors who have obtained a foreign judgment against a State are no better or worse off than those having obtained such ruling from a Belgian court.
In essence therefore the arguments on the basis of EU law are left entirely unanswered.
(Handbook of) EU Private International Law, Chapter 2, Heading 2.2.16, Heading 220.127.116.11.4.