I don't think they are actually selling those machines so well. They have a captive legacy customer base, who else is buying those?
However, he didn't elaborate or give any examples. If I were the interviewer, I would have followed it with: "Oh?! Can you provide some examples for the readers who believe that you only sell to captive audiences?"
If I had the R&D budget for an on-prem VM hosting box, I’d seriously consider their smaller Express 4, which is not much pricier than a similarly capable x86 machine.