I believe part of the problem as well with Chet was that the dreads came from Alien 3, so they had never been designed for the Predalien which is part of why it looks so awkward on it.
The art book for AVP-R does have some pretty good concept art for Chet and many of them include dreads. It's to me anyways one of those things that with a different crest or dread application and or placement would've made all the difference. Chet seemed to me pretty late-game development and despite the time they say they got, I wouldn't be surprised if they had to scramble for it which is why Chet looked the way it did. It also didn't help that putting "hair" on an Alien was new territory for the franchise.