The point is that that "dot" of Toronto GTA represents more human beings than all of Alberta.
You're judging by "geographic space taken up". Your conclusion is actually that geographic land area leans to the right, or more prosaically, that liberals move to cities and that coincidentally, oil was found in a right-leaning province.
The original assertion referred to neighbourhoods, which do tend to grow inversely to the population density. In my experience, a resident of Toronto might consider their neighbourhood to be just a block or two. While rural residents think of their neighbourhood as a many kilometre wide radius. Census/electoral divisions are a decent proxy for what we are trying to measure here, I feel. Certainly for the medium-sized rural divisions that are most relevant to the discussion.
I believe I understand what you and the parent are getting at, but it appears to be of a different discussion.
You're judging by "geographic space taken up". Your conclusion is actually that geographic land area leans to the right, or more prosaically, that liberals move to cities and that coincidentally, oil was found in a right-leaning province.