If that were true, they probably wouldn't sell any MINIs at all.
Seriously, on what logical basis do the majority of MINI buyers chose a MINI. Is it more practical, more functional, better value than most (if any) other choices. I don't think so. But people buy it for different reasons.
I think that would be a case of "see above". This isn't for people who want an estate, it's for people who want a MINI, but for whatever reasons have previously been able to justify it to themselves, or maybe their partners. The Clubman really, as much as anything, is an "excuse" to buy a MINI for those who couldn't quite bring themselves to do it with the hatch.