Activist investor Carl Icahn has this love-hate thing going on with Netflix (NFLX -0.51%).

The billionaire recently bought a large stake in the digital-video expert -- just below 10%, which will be important later -- saying that the company looks severely undervalued and might make good buyout fodder. But Netflix took a poison pill to fend off Icahn's advances, and you can just see the steam shooting from Icahn's ears when he talks about this.

In an interview with CNBC's Fast Money show this week, Icahn called the poison bill "reprehensible," particularly since the takeover defenses would trigger at the 10% ownership level. Icahn found that limit indefensibly low.

But then he started gushing about what Netflix does right, and how the company's business moat is much wider than most people think. Those 27 million U.S. streaming customers are an invaluable asset: "To begin with, I'm not sure you can build the business that easily," he said. "It's not like you build a widget factory and you start making widgets."

Amazon.com (AMZN -1.14%) and Apple (AAPL -0.57%) have been presented as potential buyers. But they're already competing in the digital-video market by way of Amazon's Prime service and Apple's iTunes store. So what's stopping these fantastically rich market leaders from just creating a better service? If you build it, they will come. Right?

But Icahn disagrees with that notion. "No matter how deep-pocketed you are, I find it hard to understand -- even if they want to spend 2 or 3 billion a year on content -- how quickly they can build that subscriber base," he said. "I don't it's possible. I think with low interest rates today, it's almost ridiculous if you really want to get into that business, not to go and spend the money to buy something like Netflix."

The company might look expensive, and any buyout bid would be sure to spark a massive auction to drive prices even higher. But that's all right, because "even if you pay a huge premium I think you get your money back in a year or two, but more importantly you get the placement, you get the platform, you get this benefit of the huge secular change that's occurring."