"Brennan said his decision to celebrate Mass with Sevre-Duszynska grew not out of some 'wild-eyed liberal' protest... ."According to the story, it occurred in connection with the annual protest at the Western Hemisphere Institute for Security Cooperation, the former School of the Americas. Maybe Fr. Brennan's former Marquette High faculty colleague, Father Cletus Healy, S.J., who apparently resides at the same retirement home, wasn't (or wasn't in a condition to be) consulted on ideological markers in our polarized Church, but the SOA Watch seems to qualify as some liberal protest.
As for the 'wild-eyed' part, Fr. Brennan supplies that. Here's a 2007 Catholic News Service report on his trip to Cuba that year.
"Father Brennan said he plans to make it again next summer. 'I'm going to go with the next caravan,' he said. 'My goal is to have an ecumenical service at the tomb of Che Guevara. ...'"Certainly not a typical middle-of-the-road perspective.