You could. But that's not what happened here, judging by the evidence on display.
All I see is what I expected to see: law enforcement engaging in a careful manner with a company that is dealing with an extremely large flow of communications. And if some of those communications are of a society destabilizing nature it is well within the mandate of the FBI to stick their noses in and make requests. You then have the option to refuse those requests, in which case you may either end up in court, they could forget about the whole thing or you are served with a piece of paper signed off by a judge.
What is illegal and what isn't is ultimately for a judge to decide but not every two-bit issue needs to go by a judge if all parties agree that the world is better off with moderating it out of existence.
The whole point is that these cases aren't going in front of a judge or jury to decide. Without that system of checks and balances, "all parties agree" is meaningless because it can't be challenged. "All parties agreed" that the civil rights or anti-war movement were destabilizing and needed to be suppressed...you seem to support that kind of unchecked power. I don't know why people are so quick to forget our very recent history.