You could also say it's the same reason asylum seekers and immigrants are called illegal aliens. It's still politics, just in a different direction. Framing something as a moral problem is not necessarily bad; it just has to be a real moral problem that justifies the proposed solution. The problem with the Iraq war was that the government lied about the problem so that they could justify a bad solution.

There is an objective difference between the terms. By mislabelling something, it is an outright falsehood, just like the lies about the Iraq war.