If there’s a current publicly-stated Twitter rule that prohibits screenshots of an internal Slack channel full of blue heart emojis, I’m not aware of it; it’s not abusive, it’s not hateful conduct, it’s not illegal, and presuming there wasn’t personally identifying information in the screenshot, it’s not private information by Twitter’s own definition as linked above.

If this was a screenshot from a Slack channel of any other tech company, do you really think Twitter would have quickly taken it down? I honestly don’t.