I like how they implemented that feature in the forum you linked to, but I don’t think that tabs would work well with infinite scrolling.
I don’t know if you’ve already thought of this, but what might work well is to use the “Reply as linked topic” feature and start the meta topics manually. You could put the meta topics in their respective categories or subcategories and then unlist those categories from showing up on the main page. That might keep the forum uncluttered.