British tried to deny democratic mandate
What was at issue in 1921 was not merely “the legitimacy of the independence struggle”, as it was with the Easter Rising and the Fenians, but whether the democratic political mandate of the Irish electorate was to be overridden by British military power.
In fact, most people were not “bystanders” on that issue — they had voted. And if most people were not active in the war, that is usually the case in all wars. Unless Dr Mansergh thinks the crucial thing was the war rather than the vote, it is hard to understand his argument. The Pearsons knew what the democracy had decided, but they chose the other side.