This move seems designed specifically to forestall calls for that requirement. Consider: Twitter are first pointing out that bots can be good, IOW "we're not ba

This move seems designed specifically to forestall calls for that requirement. Consider: Twitter are first pointing out that bots can be good, IOW "we're not banning them outright". Then they're introducing this non-mandatory bot label, which makes it seem like they're aware of bots and working on ensuring they can keep doing all the good things they do. Of course, none of this addresses malicious bots in any way. In effect, this is Twitter showing they're aware of their bot problem, but unwilling or unable to do anything about it, and are therefore doing a misdirection as a PR effort.