The predictably unpredictable Jon Stewart last week opened his show with the admission that he was suffering acute nausea. “Probably the stomach flu,” he acknowledged, as though warning viewers of an imminent eruption.I doubt if it was the flu. Stewart likely had been stewing about his imminent gig as Oscar host, realizing that his ratings on Comedy Central might surpass those of the Academy Awards. TV execs last week were playfully guessing what rival networks would put up against the Oscars this year. In past years, the slots were given over to macho movies — “Collateral Damage” and “Independence Day” in 2005, for example. Surely in ’06, however, Les Moonves could obliterate the Academy Awards if he dusted off an old “Survivor.” For that matter, Bravo might capture the “Brokeback” breakaways by re-running the pilot for “Queer Eye for the Straight Guy.” None of this is meant as a putdown to Jon Stewart, who is a truly original voice in TV comedy. Rather, it’s a reflection of the Academy’s commitment to the cause of cinematic esoterica. Add up the domestic box office grosses of the five nominated “best pictures” and your total equals that of “Chicken Little,” which was nominated for nothing and wasn’t even considered a hit. In the glory days of “From Here to Eternity” or “The Bridge on the River Kwai,” the Oscar show had shares of around 80. Some 55 million people still tuned in the year “Titanic” won, but that number fell to 33 million when the Oscar went to “Chicago.” Ratings likely will take a further tumble this year as audiences wait to learn whether Amy Adams will get the nod for “Junebug” or whether Philip Seymour Hoffman (no, not Dustin) has tightened his laundry-list acceptance speech for “Capote,” which he’s given at successive awards banquets. “If it was only about TV ratings, we’d be nominating ‘Big Momma’s House 2,’ ” is the patent explanation given by Bruce Davis, the Academy’s executive director. That’s what he told a reporter for Newsweek magazine, who was allowed to sit in on the Academy staff’s all-nighter. That’s when they figure out how to present nomination highlights in the most viewer-friendly way (“the first year that three actors are nominated for playing gay men”). These factoids are all very fine, but they only underscore the reality that not many people out there have seen “Capote” or “Good Night, and Good Luck” and that the preponderance of gay and political themes may not thrill the broad-based TV audience. Nor will an upbeat love song like “It’s Hard Out There for a Pimp” (nominated for best original song), which contains an abundance of “fucks” and other not-for-TV words. I’m delighted that challenging films with high artistic aspirations will get their moment in the sun — “Crash,” “Munich,” “Capote,” “Brokeback Mountain” and “Good Night, and Good Luck.” At the same time, there’s no denying that the life of an Oscar show producer was a lot easier back in the days when the studios displayed their riches as well as their niches — when studio fare included not only popcorn pictures but also the likes of “The Godfather,” “Lawrence of Arabia” and “On the Waterfront.” Oscar voters this year could have encouraged this phenomenon by offering support to films like “Wedding Crashers,” “Cinderella Man” or “Chronicles of Narnia.” But Academy members seem locked into a very serious frame of mind these days. Hence, TV viewers will have to find a way of catching up to “Junebug” or “Transamerica,” so they can start fretting whether Felicity Huffman will turn up in an outfit from Gucci or The Gap. And as for Jon Stewart — well, he’ll have that bigger audience back there on Comedy Central to return to.