Since we could never really quantify attitude as 50-50 vs. 51-49, I assume you just mean "if the balance of opinion lands on one side or the other, I shouldn't pick neutral". That is correct.
In fact, you should just really never pick neutral.
In all the attitude questions ever asked about in RC, there might be one in which actual scholarly neutrality was correct.
Neutrality as an RC attitude really means "lack of attitude". It means the author never introduced any opinionated or evaluative claims.
So if the entire passage is dry and informative (or only other people's opinions, not the author's), then we could call the passage neutral.
But if the author has ANY sort of pro/con language, there's attitude. The test almost never asks attitude questions on a totally neutral passage. And when they DO ask attitude questions, the trap answers are typically TOO positive or TOO negative. As you see, the author's who display attitude often convey a sense of ambivalence by mentioning both good and bad things. But the test expects you come away with the correct "on the whole, is this author positive/negative" impression.
In broad strokes, avoid extreme positive, extreme negative, and neutrality.