While at Boston University, McHenry became active with Clamshell Alliance, making several trips to Seabrook, New Hampshire to protest nuclear power.
The group provided entertainment and vegetarian meals in Harvard Square and the Boston Common after making deliveries of uncooked food to most of the housing projects and shelters in the area.
He faced 25 years to life in prison under the California Three Strikes Law, but in 1995, Amnesty International and the United Nations Human Rights Commission brought about his release.
[5] In 2021, McHenry came out as an anti-COVID vaccination activist, publishing an anti-vaccination post that said, in part, "(...) I first wrote a letter on this subject when I received an invitation to attend a meeting forming a new progressive alliance.
I wrote to invite the progressive community to stand in solidarity with the working class by refusing to meet in facilities that demand proof of participation in the vaccine experiments.