"Secure Contexts" just means you're visiting the site over HTTPS. It has nothing to do with restricting the ability of JS to communicate with the internet.
That's a misleading non-argument for the actual issue.
"Your Wells Fargo bank accounts perfectly safe from bank employees because armored cars are used to transport money. They don't let normal bank employees into the back of those vehicles. Only licensed and bonded security guards are allowed."
I'll let you in on a secret: Facebook is also controlling your graphics card, and CPU, and memory. Controlling as in "sending HTML that is then displayed via those hardware components".
And just like a media query can "access" your device orientation, panoramic media can adapt to the data from accelerometers.
The missing information here is the concept of "secure contexts": https://w3c.github.io/webappsec-secure-contexts/#intro. Being able to use this data does not mean that it can be send back to the server.