liberals discussing this here and elsewhere seem to have no problem at all with Ayers in the first place

You are a liar.

Obama has condemned what Ayers did, NOT ONE LIBERAL HERE (As far as I know) has claimed that Ayers' support of violent protest is excuseable- IF someone here defended bombings as a form of protest point it out to me, I will condemn them AND Ayers...

Those that engaged in bombings to protest war were pathetic frauds- as were those that applauded bombings done in protest.

Obama has publicly condemned what Ayers did, while McCain says of Liddy:

John McCain's appearance on The G. Gordon Liddy Show 11/8/07 includes a discussion between Liddy and McCain, whom Liddy described as an "old friend." During the segment, McCain praised Liddy's "adherence to the principles and philosophies that keep our nation great," said he was "proud" of Liddy, and said that "it's always a pleasure for me to come on your program."

Additionally, in 1998, Liddy reportedly held a fundraiser at his home for McCain. Liddy was reportedly scheduled to speak at another fundraiser for McCain in 2000. The Charlotte Observer reported on January 23, 2000, that McCain's campaign vouched for Liddy's "character":

He hired Quinn, his involvement with Keating very nearly destroyed his career... You really want to start applying your 'principles' to McCain? Or are you more comfortable remaining a transparent hypocrite?