If someone consents to your clear request to read their data in the plain, then it's not evil. Still not my cup of tea, but if you clearly explain and obtain consent, it's shady but fine.
So how is that relevant in the context here. FB did not clearly request to be able to read all traffic (encrypted and nonencrypted) so how could they get consent. Unless you're arguing, "we will monitor your Internet usage", clearly means we will man-in-the-middle all your connections. Which would be a weird take.