Furthermore of course the founding of the State was inextricably linked to Socialism.
The founding of the State was the main thrust of the Haskala movement which was inextricably linked to Socialism.
And of course the Gedolim did not object to Socialism per se.
They were busy fighting a war to rebuild Torah in the State that was being waged on virtually every front. The moral justice of the kibbutz was not exactly on the front burner.