Is there any way to 'tether' my camera via its HDMI out to a MacBook pro?
The goal is to record live, uncompressed, video direct from a camera. Thus skipping the camera's file system and recording directly onto the Mac's hard drive via Premier Pro or similar software.
Your MacBook Pro HDMI port is output only.
So no, you can not use it as input for your recording.
Your alternatives are USB 3 or Thunderbolt.