A student of mine cited a conspiracy theory website for his paper. I deducted points because I explained that a conspiracy theory isn't an actual theory since it didn't undergo the scientific method. Later, a colleague of mine stated that since it refers to a political science paper, the scientific method isn't necessarily applicable. Soft science doesn't require for a theory to be put thru the scientific method.
It might be more accurate to call them conspiracy hypotheses. But in casual use, theory is often used to refer to a hypothesis, and dictionaries include this definition. E.g. Oxford Living Dictionaries says:
1.2 An idea used to account for a situation or justify a course of action.
This use doesn't require that the idea undergo rigorous analysis such as the scientific method.
There may be good reasons to discount conspiracy theory websites as sources for a research paper, but using the definition of the word theory seems to be a stretch.