Ok. These documents have been in bidens possession for over 6 years. So, the question is, how did those documents end up in his possession? Did they accidentally get packed up in boxes as Biden was moving out? Not likely? Would they be so careless with secret documents? Also, I'm pretty sure Biden didn't do his own packing, so if that's the explanation, then does that mean that the documents were laying around so that whoever packed those boxes had access to the secret documents? Again, not likely. The most plausible explanation is that he took them, as Trump did, as other presidents before have.
Also, those documents were in his possession for 6 years? How is it that the national archives never came after Biden to reclaim those documents...after 6 years...but they came after Trump for documents he had after 4 months?