That would imply they knew about the documents beforehand and didn't just happen to come across them during a clean up of the office, as they claim. I believe Trump's lawyers were called when they found out about the warrant.
Personally, I think the Dems and the media have had enough of Biden, his gaffes and his policies. They are fitting him for a noose. Don't be surprised that when things start getting really hot for him in the House, he'll be diagnosed as mentally incompetent and unable to answer any questions. Just speculating.
I’ll leave you to enjoy your wild speculation I guess.