It allows some measure of “controlling the narrative” — the 33,000 ‘lost’ e-mails likely tied major portions of Congress, bureaucratic heads, and the President to the Clinton Foundation — by ‘finding’ leads/e-mails on Huma/Wiener’s phone they can spin it so that it was REALLY just a small conspiracy (Trust us, it was!) or, failing that, only legally provable to that small group, perhaps by claiming that the WikiLeaks/et al sources are inadmissible/illegal/unverifiable.
In short, they’re trying to pull a “TWA800” —drowning out all the voices/evidence for a missile, until those become crazy conspiracy theories— only with the size/scope of governmental corruption.
It’s way past that point, they can’t put this back in box enough to do a TWA 800 thing. That investigation was always under control. They’ve already lost control of this one.