I am reviewing an academic paper written by somebody else.
At some point in this work the second element in a list of two elements is addressed as "the last". I immediately reached for the red pen to change it into "the latter", but then the doubt came: is there any rule prohibiting the use of "last" instead of "latter" when addressing the second in a list of two elements?
I am not looking for guidelines regarding the use of former/latter/foremost/hindmost/..., there is plenty of resources already answering this kind of questions (see here, or here), I just would not like to correct something that is not wrong in the first place. Ideally a reference to a grammar that explains why using "last" in this circumstance is wrong would make for a perfect answer.