People who have been convicted of something, or who are on parole, are by definition not a part of the constitutional argument about the no fly list. The judiciary and the department of corrections can keep them off a plane if that's needed, that's their role, and if a no fly list is needed for that, no problem.
Suspected rioters travelling to and from riots, whose arrest is imminent, would appear to be the most sympathetic use of extrajudicial law enforcement action to keep people off a plane via a no fly list. I don't think there's a big problem there. It is a case that has nothing to do with the standard due process arguments against the no fly list.
I agree that using the no fly list to prevent anyone who was present as a protestor in DC from flying, regardless of whether they were suspected of having committed a crime, would be excessive. I saw shortly after the riot that the chair of the House Committee on Homeland Security suggested TSA and the FBI put protestors identified as having entered the Capitol building on the no fly list. That position, working under the assumption that people who entered the Capitol building during a riot while federal law enforcement was trying to secure it committed a crime and ought to be indicted, doesn't seem crazy.