I lurk on Twitter occasionally when a notable comment is made. Here are a couple of posts on opposing sides regarding a comment of support for Hong Kong police:
Opposition
Support

In my lurking I see patterns of reinforcement where threads consisting of like-minded people approve of tweets juxtaposed to threads of comment again, approving each other, but in stark contrast opposing the original tweet.

My going hypothesis is that patterns of blocked accounts are reflected in this effect, prevent support from seeing opposition, creating channels that to my mind bear similarity with reinforced and pruned connections within a neural net. I don't know how far the analogy actually works -- it's more of a resonance in my perception than anything I've actually taken the time to analytically compare/contrast.

As a lurker, I'm able to see both camps (public, not private). Once I engage, I suspect no matter how innocuously, how patiently, how neutrally, I will start to lose visibility as people infer a political position to my comments and seek to block my view of their tweets.

Now I think a lot of us recognize Twitter for the shit show it is. Nuanced messages won't often fit in a 280 character message (or even 10 numbered tweets)..assuming people who can or want to reflect nuance in their public comment.

But while Twitter, in its persisted concreteness, is a lovely testbed for analysis, the connections and echo chambers that we exist within is not limited to social media. We sometimes sit idly by while neighbors argue about whether a fence is too high or a Trump 2020 sticker on a bumper is a reflection of racism.

When are we obligated to enter the fray and what cost are we obligated to risk? Cost in an anonymous setting is limited to being cut off/isolated from the discussion. Once you are exposed/doxxed, costs rise.

The simplest answer is never. That taking a side is always at the discretion of the individual and never morally obligated. Simple -- but a position which, when reflected upon, leaves us mute when we look to the adult who could aid the child being bullied or excluded, but chooses not to strictly because they enjoy witnessing the strife and pain.

The next simplest answer is always. That, in situations where there is a moral component to the argument, failing to give succor to that person who is being wronged, or at minimum to speak up for peace, dialogue and resolving discord, is a moral breach of omission. This is also a recipe for absolute exhaustion if not social oblivion.

And then there is the variegated middle. Most of us, I suspect, weigh cost against benefit, the severity of the wrong, the impact of the cause and its proximity to us in calculating our responsibility and the blameworthiness of others who choose not to act.

What moral theories have a response to this question and what are those responses? Do utilitarians see that a risk of personal harm or loss of career insulates us morally for taking no action, not speaking up? What of deontologists? Feel free to reference authors/books on the topic. My education on ethics is limited in large part to Kant, Descartes and the ancient Greeks.