The extreme case is so obvious that it gives lie to the claim: if Grover Cleveland murdered someone, he would and should be tried for murder. George Washington explicitly set out with his presidency to do away with kingly privileges and be an elected public servant. If we wanted a country where the president was above any kind of law we wouldn’t have written the Constitution as we did. Other similar countries prosecute their corrupt former presidents all the time.

The closest I think we’ve come to criminal charges for a White House elected official are when Aaron Burr was indicated for murder of Alexander Hamilton during a duel, but that was before dueling was universally outlawed and the charges were dropped / he was acquitted. Being caught on tape knowingly committing a crime people are typically jailed for despite being given every opportunity to come clean is pretty egregious especially for someone who campaigned on locking up his opponent for, ya know, mixing personal and work emails and then not being totally accurate when replying to the subpoena. Slightly different from knowingly hoarding nuclear secrets and showing them off to random people.