It is until it starts making statements to the exclusion of, or against intelligent design. When faced with the idea that organized matter performing specific functions MIGHT be best explained by intelligent design, evolutionists cannot shut their mouths, even though they have nothing better to offer. Whatever they decide to offer as a better explanation, if ever such a thing should happen, it will not be science either.
And to the extent they posit scenarios that involve unobserved, undocumented events, they also depart from empirical science and step into the void of reasonable conjecture based upon their own a priori assumptions, such as uniformitarianism.