FOX is definitely not a credible source but i checked it out on other sources like the Huffington post and others as well.
Whether it's justification, excused, technical explaination, i think most people wouldn't want an app to turn on their front camera and mic whenever it chooses to, regardless of what the reasoning is.
Many other apps do this without gonig this far. As in when you click on camera, then sure, give access to it. But facebook is making it legal to start your camera, without you calling for it.
At the end, i think most people would rather not use the messenger if it means giving big brother an key to their most personal stuff like text messages and contacts. Let alone someone watching you in your house from a remote place because you agreed to it.
My 2 cents anyway.