Gay-rights activists are blasting Don Imus and sidekick Bernard McGuirk as gay-bashers, Last week, when fellow MSNBC talker Chris Matthews asked Imus if he'd seen the cowboy love story "Brokeback Mountain," Imus sneered, "Why would I want to see that?" He added that McGuirk had his own name for the movie — a crude candy reference we'll skip. The Gay and Lesbian Alliance Against Defamation called the "slurs" a "juvenile display of homophobia." MSNBC has apologized for the banter. …