Yes. Even to the end of his career (with us), he still required a double-team to stop him from scoring in the post. Which is why he and KG made such a dominant front-court before his achilles injury.
If you put an in-his-prime-Shaq into today's game, he's a wrecking machine. Especially if he's playing with 4 perimeter shooters because defenses are so spread out. If you cheat a defender back into the paint to help double on him, he passes out to the wide-open shooter. If you don't, he scores easily because no-one can guard him one-on-one.
Defensively, Shaq had and would still have his pluses and minuses. He obviously was and still would be a liability defending out in space. But if you combine him with a laterally-mobile big man (i.e., a guy like Garnett was) who can roam the high paint to handle high P&R defense, then he becomes an effective baseline vertical stopper.
Add in the fact that the modern rule change to prevent hack-a-Drummond and hack-a-DeAndre also would prevent hack-a-Shaq.