They found the material after the computers were seized for examination related to the stolen emails. As the article said, when they saw the kiddie porn they got a second search warrant for the kiddie porn. In any event, its like investigating a house murder scene and seeing drug paraphernalia on the coffee table in plain sight. You then get a search warrant to search the house for drugs as you have probable cause.
(I’m not a lawyer but stayed at a Holiday Inn Express last night - not!)
It's still fruit of the poisonous tree when you piggyback a second warrant on top of a deficient warrant.
But as I said, I fully understand that we no longer live under the rule of law. We now live under the rule of men, and whatever those men find to be most convenient.