As a technology writer myself, I'd be wary of what any review says. Most are poorly researched, press release re-hashings with little to no grounds in reality.
I'd also be surprised if they were not HDCP ready, but a computer monitor/TV hybrid is not something I would invest in or expect to be anything more than a poor example of both its components.
sailon might be onto something, but it doesn't sound like there's anything there but an HDMI<->HDMI cable. In my experience, HDMI being digital either works, or it doesn't. And any cable costing more than a couple of bucks offers nothing more than good build quality, if that. Either the Apply TV is lying, or the displays themselves are at fault.
A logical solution would be to try a "real" television which has successfully worked with HDCP content before, to rule out the cable and/or the Apple TV itself.
HDCP has been cracked in software, rendering it effectively useless, and yet us consumers are saddled with its horse**** for the rest of HDMIs life. Thanks for that.