I was thinking the same, just didn't want to promise anything in case I could not deliver. The devs are VERY eager for feedback though, so it's truly doing them a favor to ask, plus as you said most likely also a significantly wider userbase as well. Then again I think I've already asked for something vaguely similar in terms of general transparency features, although this is concrete hence much more likely to move forward (otoh there is a distinct possibility that I've already asked for precisely this, so I'd have to look it up). Edit: okay, done - https://discuss.online/post/46939614.
We seem mostly in agreement on other factors as well. Stoicism suggests that we cannot fix the entire world, we can only do what we can in our little corner of it. Personally I would hope that PieFed.zip would automatically apply a user-level block to new joiners for Lemmy.ml, the same way that it already does for hexbear.net and Lemmygrad.ml. Bc whatever we personally think about tankies or magats and how much we can stand to put up with their alternative factual argumentation practices, it remains that new people are extremely put off by such, and keep fleeing here when exposed to it, then subsequently complaining about us to anyone who will listen.
i.e., being kind to and/or having empathy with people who enjoy trolling behaviors is not the same thing as offering them a platform. Especially one where their messages are presented identically alongside with all other messages, such that new joiners cannot distinguish between them. A warning label, an icon, a different color highlighting etc. would go a long way. But that's a ton of effort, which anyone using a 3rd-party app won't be able to access anyway, hence blocking is all that is left, short of full defederation.
The alternative, which is the current method, is to simply get comfortable being a troll bar. We feature trolls here, we make them feel very comfortable, and offer only confusing methods to people and very little guidance to new joiners to avoid them.