This website contains age-restricted materials including nudity and explicit depictions of sexual activity.
By entering, you affirm that you are at least 18 years of age or the age of majority in the jurisdiction you are accessing the website from and you consent to viewing sexually explicit content.
I think what ends up happening (as a rando without a legal degree) is that the backpack and all of its contents become inadmissible as evidence. It makes beyond a reasonable doubt harder to achieve for the prosecution because they lack a proposed murder weapon in evidence.
This is just a motion. Judge will decide it’s validity and the remedy. It might end up with the evidence excluded, but it might be that the prosecution just has to provide a different/stronger justification, or even be a nothing burger if the judge is unconvinced by the arguments in the motion.
I agree with your analysis if the judge does exclude backpack and contents as evidence.
Anything other than exclusion will be grounds for appeal, later, too.