Where do you get that? Members of Congress can be arrested, tried and convicted like anyone else. The narrow exception is the "speeches and debates" clause, which immunizes members of Congress from punishment for official acts performed while Congress is in session. It is theoretically possible for someone to remain a sitting representative while in prison. I do not know of a case where that actually happened.
Your reference to "the leadership" has no constitutional basis. The Constitution provides for the offices of Speaker of the House and President Pro Tempore of the Senate; the majority leader, minority leader, whips and committee chairs are important to the process, but their offices cannot be found in the Constitution. The Constitution deliberately -- and I believe, naively -- did not predict a two-party system.
A member of the House or Senate can be expelled by a majority vote of each house's membership. Not its leadership. In practical terms, it's unlikely a vote would get to the floor without the blessing of at least one party's leadership, but that is a practice, not a rule, let alone a law.
Adam Clayton Powell, D-Harlem, was convicted of corruption and expelled by the House. He ran for re-election and won. The House voted not to seat him. SCOTUS ruled that the House's power to judge the "qualifications" of its members did not allow it to disqualify someone for actions before the last election -- the people are the ultimate sovereign, and the people of Powell's district made their choice.
BTW, neither the Executive nor the Judiciary are considered "representative", and are a source of possible tyranny. In conflicts between the House and the Executive regarding the status of the members of the House, the Constitution clearly establishes the House as the superior body.
When it comes down to brass tacks, the most representative -- or in other terms, the most democratic (note the small d) -- government body holds the trump card. That's the House. Or, if it comes down to the need for a constitutional amendment, the state legislatures.
Remember, to stick Jim Traficant in jail the House had to eject him.
Not so. Traficant was tried and convicted and headed to prison before the House expelled him. I suppose there might have been a scenario where he might have avoided custody if he remained on the Capitol grounds and the House hadn't given him the boot.
No one, aside from Traficant, wanted to ride out that kind of farce. There were only two votes against Traficant's expulsion -- one was Jim Traficant, and the other was Gary Condit. Condit had already lost his re-election bid and was widely suspected of killing his intern/alleged mistress, so I assume his vote was to make some kind of point that made sense to him at the time.
That's why they expelled him (See Article 1, Section 5, Clause 2.)
Bet you missed that part during all the myriad of discussions we had regarding the impeachment of Bill Clinton. Still, there it was, the clause that dictates that the House must organize and have a Speaker is in there right before the impeachment part.
Again, ground glass, your knees, supplicant posture ~ we are patient.