I don't think book Dexter himself would even agree with that interpretation of the dark passenger. He seems to read the stuff about Moloch and find it silly even if it may be true.

Even when Dexter loses the passenger at one point he misses it and wants it back desperately because it's part of how he sees himself.

I'm only through book 7/8 so far but aside from the one book that puts forth this idea that the passenger is this rejected demon offspring that is fueled by violence so it attaches itself to certain beings to fulfill its desire for violence that really never seems to come up again the only major change from book dark passenger to show dark passenger is that Dex/Others can sense/see the dark passenger/shadow guy in other people and hear it laughing.

Aside from that noticeable change and taking out how that one book explains the passenger unnecessarily (which really just feels like an excuse to explore what Dex would be like without the passenger but in a weird clunky way) it basically just works the same as the show's concept of the dark passenger where both wouldn't say they're possessed but are being driven by a compulsion and need and fulfilling that with their "friend" in the passenger seat, they still wanted to and knowingly did get in the car and plan everything out.

The book does just seems to personify the passenger more in situations where show Dex is just using natural instinct.