We tend to define ‘emotive’ or ‘emotional’, especially as opposed to ‘rational’, as a state, or reason (in the sense of motive) characterized by the presence of emotions.
But a reason for doing something can be ‘emotional’ if it is characterized by the absence of emotions as well.
Suppose that some-one fully understands the rational ethical arguments for vegetarianism and knows that they are valid because s/he cannot find any fault with them, rationally.
But suppose that this person, nevertheless, continues eating meat because s/he emotionally does not care about the issue and likes the taste of meat.
Then, this behaviour is not dictated by reason (reason commands the opposite), but rather by emotion (lack of it).
In this case, it’s the lack of emotion that leads to a behaviour that goes against reason.