The discussion pertains to a political position, and all political questions are fundamentally normative ones, on the "ought" side of the gap. Both intended aims and ethical limits are defined by what you're calling "ideology".

The "is" side of the question defines the empirical constraints within which those aims are pursued, but that's an instrumental question: it bears out the means, but has little to say about the value of the ends.

In other words, "is this course of action likely to produce the outcomes we intend?" is a question to be substantiated by evidence, but "are these the ends we wish to pursue?" and "are these ends worth the cost and/or risk to other things we care about?" are normative questions for which subjective values ("ideology") determine the decision criteria for all parties in the debate.