I read the very long court opinion (for two dang hours) attached to that as No. 4. When it says it was obsolete, it meant that there are few "protections" for members of Congress anymore. For example, there was no defined felony for "perjury" back when that was written, but now there is. In fact, it is discussed at length in that SC Opinion. So while Schiff, for example, is protected from a "civil" lawsuit for lying his ass off during impeachment proceedings, he is NOT protected from the perjury laws because it is a federal felony to commit perjury in Congress. I think what Q was trying to show everyone is that lying on the floor of Congress during an official proceeding is not as "protected" as members of Congress continue to think since "perjury" is a federal felony now. The part that is almost obsolete, per the opinion, is that most common laws for felonies were not in place back then, so most congressmen can now be indicted and charged for things they may have got away with back then.