I've seen the exact opposite view promoted within the fediverse for the past 5 years: that its design is anti-viral, that it does not provide a good space for the dissemination of disinfo, and from my own partial view of the fediverse I would agree that it does not appear to do so.
The fediverse of the past 6 months is much bigger so it is possible it has changed.
[Facebook NDAs are a recipe for rumour; fedizens have a right to speculate about what may be happening.]