I don’t think it’s fair to say that it’s “yaduah” that the Raavad misunderstood the Rambam. As a Rishon who wrote a pirush on the Rambam, he probably understood it better than anyone else of his generation, kal vachomer anyone of our generation.
The fact that the Rambam explained it more in Moreh Nevuchim does not negate the Raavad’s problem with the Rambam: namely, that he felt the Rambam’s explanation did not sufficiently answer the question, and therefore the Rambam should not have brought it up at all.
The Raavad says “v’chol zeh einenu shoveh li” about his own pshat too; so his problem is not with the Rambam’s terutz per se, rather that since this question is so hard to answer (and admittedly they do have different approaches), the Rambam should not have brought it up, and the Raavad only wrote his own approach because the Rambam brought up the subject.