Not voting communicates acceptance of the current regime. Voting for third-party/write-in candidates communicates dissatisfaction with the current regime, as it is a (symbolic) attempt to change it.
As is believing that politicians would interpret a low voter turnout as anything but a net gain - it just means they can expend less effort required to shift the balance in their favour.
"Politicians" collectively win no matter what. Particular politicians and interest groups have varying strategies for high and low voter turnout and various vote compositions.
I fail to see what is magical about not bothering to make a move when they win either way.
