Legal will certainly advise leadership they can continue claiming that the system treats everyone equally, because scope of the word system includes the entire Trust organization people + automation, and “equally” can mean almost whatever Mark needs it to mean.
“Senator, thank you for the question. We treat everyone equally. To be clear this means every single user on our platform is subject to the same terms of service they agreed to when signing up.”
By the definitions you're using, Mark Zuckerberg personally logging in to the database and type DELETE FROM USERS WHERE "Policital_Affiliation_heuristic" == "Conservative".
So fine, if you want to define the words as meaning something they clearly don't, and want to try and fight that battle in the media... ok. But almost certainly the first thing that happens is something exactly like this - some nerdy engineering comes out and goes "Well no actually, we manually intervene for the people we like". And then you get to go back to Congress and explain to them why you clearly lied to them, and you're not going to get out of that by using Mark Zuckerberg's pure eye-watering levels of charisma.
“Senator, thank you for the question. We treat everyone equally. To be clear this means every single user on our platform is subject to the same terms of service they agreed to when signing up.”