The Republican report says, in effect, "You were not prepared for just how awful Trump's supporters are." That is a valid criticism, because they are truly awful. That McCarthy doesn't see the irony in claiming that security couldn't handle his side's mob is typical of his hammy hands.
Don't worry about the Republicans governing. Without the Senate of the White House, all they can do for the next two years is get in the way and masturbate. I expect they will do both.