Nice try, but the Attorney General does not sign warrants. A judge approved the warrant. The FBI had no legal warrants, this was well explored in the 1970s during the church commission investigation
In this case and at this time the Attorney General DID sign for the surveill.
Hoover went to JFK and explained that Levison, formerly the Treasurer and officer for CPUSA, was now working for King, and they wanted to a wiretap/bug.
Kennedy Bros. said they would talk with Martin. Both spoke with MLK and he refused to dump Levison. Bobby signed and that order was in place till the end.