Maybe so. But that isn't your original claim. "Historians are perspectivally bound" and "the very goal of history is to provide an apologia for certain political ideas" are two very different claims. The first hardly assumes that latter, that because historians are bound by ideological perspective they necessarily function as political hacks, and the latter doesn't actually assume the latter, that because somebody writes history with ulterior motives, that is the only way it could be written. (You'll recall that the early empircists were strongly critical of earlier historians who they believed to be guilty of this approach, but themselves firmly believed in the possibility of truthful and accurate history.)