I'm nowhere near the investigation, but I'd imagine it has more to do with the clerks and aids who did the boxing and inventory than with either president.
I've seen a number of mishandling of classified info cases over 15 years, starting at the FRS. An FRS peer left an NTRP in his car for a week (we used to be able to transport them between buildings at HS-10), and he continued on to his fleet tour. Maybe an LOI, but no career effect. An aircrewman minding the library gave an ASW TPG instead of the SAR TACAID to a foreign national - oops. No mast, IIRC.
In the fleet, I saw LTs leave safes or vaults open and get LOIs, not separation or jail time. We also had an AW lose a laminated S/NF placemat out the cabin door in theater. I'm sure the CO wanted to crush him, but I don't think it went past a DRB there either (it was the CO's idea to laminate them...)
In the end, it's a spectrum of impact and intent when investigating these goofs, and I'm not worried that a small percent of sailors (or officers) are too politically biased or anti-authority to understand that neither POTUS nor ex-POTUS are likely culpable for the mishandling.