1) I disagree. I believe Mozilla is right, and engineers should consider the ethical implications of the things they're asked to build. This argument would be valid even if made by Mark Zuckerberg himself.
I'm fairly certain that the parent meant to say that the original criticism of Mozilla did not make any statement about whether the content of Mozilla's proselytizing is right or wrong.
Nobody has claimed that Mozilla's argument is invalid just because Mozilla are hypocrites for making it. People are expressing displeasure over Mozilla's hypocrisy, which is a valid issue, orthogonal to the merits of their proselytizing.
Edit: Sorry if I come across as belaboring, I hadn't read your other post. :)