That's probably a ClearQAM signal that he is receiving. Most HDTVs in North America have dual-standard 8VSB/QAM64 tuners so they can receive both broadcast and cable channels. No CableCard required.
It's more likely that it's a mix of that and analog. In Las Vegas at least, Cox makes all channels below 100 available as unencrypted analog video, receivable by pretty much every TV built since the '40s or so. Local channels (including the subchannels many of them have offered since the digital transition) are also available in unencrypted digital form. It works out to probably somewhere around 70-80 channels, with maybe a half-dozen in HD, a dozen or so in digital SD, and the balance in analog SD.
I cut off TV service about a year ago, switching to data-only service. They've not bothered blocking these channels, so they're still available. My TVs are set up to tune them in, but I can't remember the last time I watched something that wasn't streamed from across the Internet or played back from the file server on my LAN.