Mancini wrote for the Hannibal tv show for a bit which is what gave him the confidence/idea to try this way. He wrote all the original films/co-created the franchise. Good reason to be on board imo, if anyone gets Chuck its him. He even recognizes that the 2nd film is probably the best one/scariest for a variety of reasons. One of them being that a killer doll just isn't that scary unless you're like 6-14 years old lol but he's trying to recapture some of the spirit of that 2nd movie with this show.
Side note, part of why I think the movies went into such a weird direction is because of that fact but the late era Chucky films (Bride, Seed) are fun as hell in a horror comedy kinda way. They're very self-aware before that was a big thing. They should find a way to bring Redman back lol