This sounds fishy to me.
I don't believe it's true.
I think the feds are so desperate to look like they can actually control the cannabis market by intimidation, that they make up 'wag the dog' stories to make themselves look good. If there ever were gardens, they probably planted them just so they could 'find' them and deport some poor illegal Mexicans to make a big show. Like a giant game of liars poker. They just declared five aces.
I call their bluff.