If the male keeps producing megaE pups in every litter, I'd say he has the dominant version of the gene that causes the disease. At this point, the sire just shouldn't be bred. But what are you going to do about it? Even without mentioning the male and the owner's name, it sounds like you're dragging this guy through the mud. He's wrong to keep studding his dog, but 99% of the people out there wouldn't keep doing what he's doing. If the dog is constantly producing megaE pups, with different females, its clear that something else is going on.
I think in this case the male probably has megaE and it just isn't presenting itself...or it is and the owner is covering it up. The sire's owner is definitely not the most ethical person, but again, most people aren't like that. Yes, without more information no one can really say more about what is going on, but hopefully people will stop asking him to stud soon because they will hear about the kind of progeny he's producing. Natural market forces will cause him to stop breeding this male at some point.
At this point...its not even about megaE, its about ethical breeding practices. This one doesn't care at all, he'd breed this dog no matter what disease he was producing.