Everyone who chose not to vote effectively removed themselves from the set of people to be counted as either supporting or not supporting this administration.
That's not actually how 'support' works, especially when 'the' alternative was committed to arming a genocidal apartheid regime against the will of their own voters. Many. many people can no longer stomach to 'hold their noses' and vote in favor of open atrocity.
There's a whole lot of people who strongly disdain both parties, on that basis and others. They are not remotely proportionally represented by either government or media, but they do exist and they don't support this administration.
Btw, there are all kinds of electoral solutions to the two party bind which you seem to have entirely accepted. Neither party will ever willingly bring those in.