As much as facebook is a thing I love to hate, I don't see the problem there. It's not because you have an onion site that you are forced to allow any content whatsoever, and in fact many onion services explicitly forbid certain types of content for good reasons.
You're free to not connect to their platform either way (and to be subject to their limitations regarding contents and behaviour), whereas setting up an onion service can be about stuff that people aren't free to avoid (i.e. censorship by the only ISP they might have, by a state, etc). There's no issue with consistency there.
You're free to not connect to their platform either way (and to be subject to their limitations regarding contents and behaviour), whereas setting up an onion service can be about stuff that people aren't free to avoid (i.e. censorship by the only ISP they might have, by a state, etc). There's no issue with consistency there.