The biggest hurdle to that idea is that the same report that reveals the Serkis rumor indicates the casting notice for Penguin is looking for somebody 20-40 years old, and Serkis is 55.
The Penguin, The Riddler, Two-Face, and the Mad Hatter have all been rumored to appear in The Batman. Honestly, Andy Serkis could potentially play any of them.
Although, it has to be said that Serkis as the Penguin has a certain feel to it that seems right.