The quote comes near the end of an Ibbotson column in The Globe and Mail, the liberal version of "Canada's national newspaper". It doesn't matter what the subject of the column is, because this fragment is entirely irrelevant to it. It doesn't even matter that the fragment itself names "rural voters", because the clause could just as well be applied in any other context to almost any other way of grouping people that wasn't, explicitly or implicitly, by race. The vast majority of urban voters in Canada, for example, are also white. The real point is that the phrase pops up in a column that has nothing to do with race at all -- the point is that, on anything remotely resembling a rational basis, it has no point.
Why is it there, then? Ibbotson could just as meaningfully have said something like: "Rural voters, the vast majority of whom speak with a rural accent....", or "Rural voters, the vast majority of whom are native earthlings....", but then the absurdity would have been too obvious. Why not in this case? The answer, sadly, is a sick political phenomenon on the liberal-left called "racialism", which is increasingly defining itself by its demagogic use of "race" as a simple club in any kind of political issue. What Ibbotson is doing here, then, is signaling. He thinks that by waving this sort of phrase he can tell people, at least his people, the bien pensant lib-lefties, that a) he himself is not a bigot -- because notice how racially hyper-aware he is, bringing up race even when it has no particular application, but b) the people he's talking about could very well be bigots (the "vast majority" are white, after all), and so the side of the issue they favor, whatever the issue, is plausibly the bigoted side.
It's fast becoming the story of the boy(s) (and girls) who cried "Race!", of course, and with the same sad result. That they can't see such a result, and resort so easily to such crude and ridiculous racial signaling, is an indication of just how impoverished the liberal-left has become.
For an alternative view of race itself, see this brief clip from a Morgan Freeman interview.