OK, so I'm going to follow your theory here and meter towards the camera and follow your argument about physics as you're a trainer and are teaching, perhaps this will be something new to me.
I'm also going to meter towards the light for my setup - which is exactly as I've been taught and how Mr Elliott is positing.
Time to see which one is right.........
Split-lit-meter-to-camera by
matty27272, on Flickr
This is badly blown all down the left side when I metered to camera.
Split-lit-meter-to-light by
matty27272, on Flickr
This is NOT badly blown when I metered towards the light source.
CONCLUSION of the simple experiment
If you want the meter reading to be right and not give you blown highlights, meter towards the lightsource and not the camera. Any argument that you only need to meter to the light source in certain situations is going to set you up to fail when you forget which situations to do it in. Your meter may well have a dome which reads light from 180 degrees, but unless you ALWAYS have your lights in the same position, you're going to forget and end up with a potentially expensive mistake.
If you don't want to believe me, just set up your lights (or single light) and prove it to yourself. Move your light to different positions and do 2 shots on each light position. One towards camera and one towards light source. Keep doing this until you run out of space on your memory cards or patience for the experiment.
My mentor tells me how to do things, shows me them working and then sets me homework to do which involves me proving the things to myself afterwards. I suggest that this is the way to do things. See the setups and arguments put forth by people who are offering training, watch their proofs and then prove it to yourself.