Clearly in this case saying that he's qualified on segments just means that he's waaaaay over the diamond MQS level. You can't qualify for million miler status on segments, it's just a figure of speech.
I interpreted the statement to say that he earned DM every year by the segment requirement rather than MQMs, but as someone pointed out, only MQMs count for MM status.
Another historical question for PMDL folks: When did it start to become possible to earn MQMs from DL AmEx credit cards and was there a time when simple spend on a CC became status miles without limit? I know on some airline programs, certain old timers earned lots of miles from CCs back in prehistoric times like the 1980s and 1990s
He might *only* have been top tier DL elite via segments, but maybe he also had a bunch of MM miles from PMNW, and others such as Republic and Piedmont that became part of DL at some point.