You are 100% correct. And here's the real irony. Newton would surely have rejected today's creationism both with and without the benefit of today's better science.

I say "with" because as a scientist Newton understood the need to look at evidence impartially and objectively. In his day there was compelling evidence that the earth revolved around the sun, though the Bible essentially states the opposite. Newton accepted this, however religious he may have been. There was, however, little of the compelling evidence available today that suggested evolution or the age of the Earth, which is why he (and pretty much everyone) was a comfortable creationist.

I say "without" because the premise of a "young-earth" today is not what it was a few hundred years ago. Taking every word of the Bible literally is largely a product of the 20th century - most typically the latter 20th century, and has more to do with politics than with an honest wrestling with the word of God. In the 1600s, a lot of the Bible was accepted as metaphorical and allegorical, as invested with truth and not necessarily fact: camels through the eyes of needles and all that. Todays' creationism is an abomination that flies in the face not only of accepted science but also of respectable and rigorous theology. I think that Newton would be repulsed by creationism today.