One read on this may be that lemmy.world may not be the best instance upon which to host !austin (i.e. if, for whatever reason, they're not able to maintain federation with other instances).
Another thought is if you really want control over your "home" instance's federation you could host your own instance and call all the shots. I've been considering doing this but mostly out of curiosity. Admittedly you would probably want to be fairly technical for this to be a viable solution.
It also looks like the Lemmy devs have been considering the possibility of implementing profile migration between instances, which could be interesting.
All of that said, I'd be curious to know the specific reasoning given by your last instance on why they decided to defederate. I don't want to sound accusatory or jump to conclusions but this kind of post strikes me as... FUD.
I love their cinnamon rolls. Hope you have better luck next time around.