In this case the probable cause was that his name was on a terrorist watch list. something that the TSA and the FBI wouldn’t have known was done out of spite with no real justification. The search was as legal as it could be under the circumstances. Though access to the phone gets murkier because it falls into the bullshit reasons cops claim all the time to search or arrest you. They admit that they had no real evidence to hold him. claiming CSAM was likely to scare him into opening the phone for them. But the core issue is that he was on a terrorist watchlist and that is just cause. I’m not saying he should have been there but the issue is ultimately with the police department not the FBI or the TSA.
It’s a whole lotta bs and I hope he makes it through unscathed to sue the police department for their actions.