In other words, this is not a coincidence involving an unrecognized browser on an unknown platform. It's deliberate. The networks don't want services like Google TV to cannibalize their cable subscription model too quickly by making Internet video more appealing. Even though they realize it's inevitable, they want to slow the progress down as much as possible so they can keep making money.
Google is taking the route it usually takes when owners won't let them have content for free: it's negotiating and trying to strike a monetary deal with all three networks, according to Reuters. Fox is also considering blocking access to shows on its website, but it has yet to make a final decision. Google's negotiations are necessary if Google TV is going to become something that does more than just broadcast TV channels, content from select programming partners, and basic YouTube videos.