I was advised not long after you posted this thread you logged a complaint so you would/should be getting updates from the assigned Customer Relations representative.
The last update I got was: Our app definitely does not launch Facebook. We have asked Facebook to take a look at it as well; we’re awaiting a response from them.
I have asked for another.
Err as per the last screenshot and here is one from today.....your My Optus and Optus Sports both launch Facebook. What part is hard to understand? I have restricted my Facebook app manually from being launched by secondary apps.
I can confirm it is still being investigated by the Optus dev team.
I have requested another update from the Digital team.
Have seen no other reports of this.
I could be mistaken by that e-mail address listed seems to be a general one so if that's the case likely receives heaps of e-mails. If you didn't already I would suggest leaving a review as you'll see they get responded to rather quickly. Although reading through some they do mention that e-mail address so you should hear from them soon.