It doesn't necessarily wholesale invalidate it, and it depends on the context. The danger is that if the claim is, for example, "they are making a hostile environment for $MINORITY", if statements exist that say "We are just doing this to avoid liability", those could easily be interpreted as indicators of insincerity and that the bias exists. Whereas, if they at least appear to be True Believers, it is harder to call that into question.
It also hurts from the PR angle, for basically the same reasons. News outlets don't want to be seen as tools of the machine spreading corporate FUD and saving BigCo from liability. They want to see themselves as noble soldiers on "the right side of history", and they want the public to see them that way too.
It's therefore much easier to get coverage, which will be useful for establishing your non-bias, if you don't tell everyone "we wouldn't be running this program and enforcing these 'everyone play nice now' codes if we didn't feel there was a meaningful legal risk involved in not doing so".
It also hurts from the PR angle, for basically the same reasons. News outlets don't want to be seen as tools of the machine spreading corporate FUD and saving BigCo from liability. They want to see themselves as noble soldiers on "the right side of history", and they want the public to see them that way too.
It's therefore much easier to get coverage, which will be useful for establishing your non-bias, if you don't tell everyone "we wouldn't be running this program and enforcing these 'everyone play nice now' codes if we didn't feel there was a meaningful legal risk involved in not doing so".