with about 27.8% not voting and who have to be assumed to be happy with "whatever the outcome is".
That's a pretty huge assumption. You could also make the assumption that all of the non-voters were happy with the status quo and felt their vote wasn't required because no one would be so stupid as to vote leave without a plan in place, or at least a skeleton of a plan. But, of course, that doesn't fit your cosy world-view, does it?
The reality is that no one knows why people didn't vote or what their intentions might have been had they voted.