Far as I know, Hulu is owned by NBC. They already own the content. They can do what they want with it. Comacast (and other cable companies) don't own content. They can't do anything with something they don't own (or license). It's that simple.
But also, I don't know why the cable companies want to have a website for internet TV. They say it's not for revenue, and it certainly couldn't be, a big website like Hulu costs a lot to develop, and while I like Hulu, it doesn't make me think any more or less of NBC, or earn them any goodwill.
Yeah, they make money from advertising, but it can't come close to what it cost to develop the site.