Lindtner was never a Buddhist as far as I know, he was/is a scholar of classical Greek, Latin and Sanskrit who happened to do his ph.d. on Nagarjuna, was a professor for some time, and then got fired in the midst of this Holocaust thing and other controversies.
So I think if there is any link between his eccentricities and Madhyamaka it's probably only the fact that you have to be something of an eccentric in the first place (though not in the negative sense necessarily) to be working with Nagarjuna at a doctoral level in a Western European university, when you're not even a Buddhist.
I don't know the guy but I heard about him since I'm also from Copenhagen and he made it to the headlines a couple of times. It's a small country and it doesn't take much to cause a stir. But for what it's worth I think it's good that it appears like he now moderated his late-1990s very stereotypical and very unacademic "Holocaust denier" opinions. Although his views still seem to be out there it's a big improvement that he gave up on at least some
of the fallacies of conspiracy methodology.
Maybe his other controversial views (the Jesus is Buddha thesis) is enough controversy for him these days?