My guess would be that they can't and just do it anyway. You didn't say if the VPN was required, or if it's some crude looking outfit. I know I've been streaming Patriot's games for 4 or 5 years, and I have no doubt the NFL wouldn't approve. I figure that as long as not too many people are paying attention the NFL won't either. I also know that the sites that stream live sports tend to be dodgy as hell. I always tell people to install two ad-blockers before trying to go there, because one won't be enough.
edit: Now that you've shown the link, I think my notion is correct.
edit 2: I also just noticed that it's NordVPN. That pretty much clinches the piracy aspect. I'm about as pro-piracy as you get, and those people will absolutely deserve it when they get busted. Running a VPN is great. Operating pirate sites so people will use your VPN is just asking for trouble. Mark my words, before too long, clicking on one of those channels will pop up a message saying that for your own safety you can't access it without a VPN, and only Nord's will work. I've already run into this with TPB mirrors, which are all sponsored by VPNs.