From my perspective as a long-time lurker and very occasional poster...
This has all appeared extremely silly, ngl. That might seem dismissive to some of the people who were involved in the very heat of it, but I don't really intend it to be. Overall, the optics from a largely outside observer on all of this haven't really been great, but I feel like that starts to tread into water that's not terribly relevant for the original point of this thread, so I'll attempt to stay on topic.
First off, if you genuinely want to make MSB a positivity-focused environment, you have to understand that you're going to be fighting an uphill battle. The reputation that MSB inherited from WORA and further refined with the Hogpit isn't one that goes hand in hand with 'calm and measured discourse.' You're undoubtedly going to have a lot of people who will try to continue to foster the more hostile environment the place has been known to be for a while. It feels a bit like an Applebee's just bought out a biker bar, so expect the bikers to keep showing up for a while, either in protest or ignorance. Honestly, if I hadn't been watching what's been going on, if someone told me that MSB fractured and a new place opened called Brand MU Day, I definitely wouldn't be putting money on MSB being the one all about positive discourse from here on out.
Anyway, that's just one of the two main hurdles I see going forward. The other is that... like... You're humans, too. You are not immune to tribalism and cliques anymore than the Brand MU Day people are. Be wary of the urge to label any criticism or opinion that you dislike as being hateful or insulting. This is the internet, disagreements are going to happen and they will get heated. Think hard about where you want to draw the line and make sure you make it clear where that line is.
Mind, none of this is to say I've seen evidence of any of this so far. It's just a general warning as someone who has seen and sighed his way through repeated fractures and merges as a comic game fan. Generally speaking, I'm all for a positive environment for discourse. Once upon a time I would have thought it was impossible on the internet, but over the years I've seen a few examples of it (mostly) working so... I'm rooting for you guys, but I wouldn't say I'm totally convinced of the viability of this experiment yet.