It’s called intimidation. I don’t know who is behind it, most likely Mueller. But the idea was to intimidate Stone and anyone else who might be facing Mueller’s gestapo squad.
Some would even call it terrorism.
I think it’s more likely propaganda.
Poison the well of public opinion.
It gives the impression that this is a very had individual. Why else would so many LEO be needed if not for that fact.
Then the judge slaps a gag order on both sides and the lasting impression is this guy must be guilty of terrible things.