IMHO, you shouldn't have to justify yourself ("yeah yeah, this is not optimal, I know it because I am not an idiot"). Just write your code in O(n) if that's good enough now. Later, a developer may see that it needs to be optimised, and they should assume that the previous developer was not an idiot and that it was fine with O(n), but now it's not anymore.

Or do you think that your example comment brings knowledge other than "I want you to know that I know that it is not optimal, but it is fine, so don't judge me"?