Admittedly, I have stopped following the league closely, but I like the Williams acquisition. I don't think there is any conflict between Williams and Maluach. In the incredibly unlikely event that Maluach emerges as a starting-level center, then you have a decision to make, but that's years down the road.
Remember that the Suns passed on Haliburton because they didn't think they had room for him with Chris Paul already on the roster. That was a mistake then, and similar thinking would be a mistake now. Rosters turn over so quickly that, unless you're talking about players on enormous contracts, you can always clear a logjam if one happens to emerge. I am completely unconcerned about the possibility that the Suns may have too many big strong centers.