Communities are best served by an instance more tailored to their content. General instances are good and convenient for people new to the platform, but they're dangerous to communities. Think of all the beehaw.org communities that are effectively quarantined from .world users. Not that defederation is wrong, in fact I'm a huge supporter of defederation as a whole. But putting relevant content onto a more relevant instance will ensure that the community will be more likely accessible, broadly, to users regardless of defederation.

If .ml wishes to not have anime content, that's entirely their prerogative. It's important, then, that anime be moved to somewhere that is is welcome, or else those in the community may find themselves without a community at any given time.