Not sure what you mean? In what way is the update 'forced'? It's not being silently installed, it's not like existing apps will suddenly stop working if it isn't applied.

This is only "forced" when you look at it from Facebook's perspective, as it'll directly impact their app, they don't control the OS version of their users. But they specifically used the loaded phrase "Forced update" to trigger an emotional response from the reader. Paints Apple as a malicious antagonist.