And the FBI had "0" right to take any of his personal papers...and that's afforded to each and every one of us under the Constitution.
Hillary, Bubba aka Socks, Biden, Pence and probably 1000 others had Classified files. None were entitled....none were prosecuted...and in fact the NARA told Bubba to keep his tapes. And Comey said no one would ever convict Hillary...and every one says that Biden is a really good guy...etc etc.
Ok, you have articulated a couple of reasonable approaches the Trump team might take. One problem might be that even after being told about the classified documents, Trump resisted returning them and allegedly took steps to prevent a thorough search even by his own attorneys. As to the fact that others have done as bad or worse, I agree with you, but that is a political argument, not a legal one. Selective prosecution claims are very difficult to win in court.