(as a person who works in upper-level IT for a large public university and could make this decision) My biggest concern is not hosting costs in terms of compute, bandwidth, or storage. Like the article said, It’s in the human cost of moderating local communities, moderating the defederation lists, and in explaining to parents why their kid seeing goatse on lemmy.uni.edu via some federated troll instance is not my fault.
The mod tools really aren’t there yet for it to be worth the risk I think, but I will be honest I’ve thought about pitching it.
If they don’t matter currently for moderation I have to imagine they’ll be part of a moderation toolkit eventually. Leveraging community voting to detect spam would be decently effective, especially for fresh accounts.