[BBB333]

As I recall, Ayers was set free because a judge ‘lost’ all of the incriminating evidence against both He and his Wife...so there was no trial.

[Fedora]

The Church Committee also had put pressure on the FBI that made it harder to prosecute Ayers' case. They still had Dohrn dead to rights for crimes committed more recently than Ayers' bombings, but Ayers' dad managed to get them both off the hook. And they remain very active:

Obama Secretly Partied With Bill Ayers Last Summer (February 12, 2014)

Bill Ayers believes opposition to Trump should come from the people—not the Democratic Party (January 18, 2017)