Meta was correct. "Exigent circumstances" to the 4th amendment warrant requirement did not apply, because there was no known potential victim at risk. So the cops needed to have a judge sign a warrant. Didn't take long.
that's a slippery slope and exactly why we have a legal framework. "give me hsbauauvhabzbs private messages because he might send CP and thus it's your moral duty!" can be applied to everything. "oh, we didn't find any CP but we now still have their private correspondence on file."