There are devices that will give you HDCP 2.3->1.4 conversion for compatibility reasons (or maybe wink-wink reasons), and after that you can use a HDCP 1.4 stripper. There are also devices that will strip 2.2 outright (they are marketed as HDMI splitters but, oops, one of the two outputs has unencrypted signal, an honest mistake); not sure about 2.3 though. Completely agree that HDCP makes everything harder, but in this scenario it would also make attacker's job of descrambling the eavesdropped signal harder. And this is after they have overcome packetization and spread spectrum hurdles, which the paper suggests is very challenging to do, so would be a (hacky) defense-in-depth for DisplayPort. Even more important for HDMI/DVI which lacks the aforementioned hurdles.