I’m aware of many people that have/had two phones(myself included). And even if Citadel was inclined to look at the phone the only phone that they could possibly look at is one that Citadel provides for exclusively for business. If they provide a stipend for mobile phone which many companies are moving towards. Then the phone is considered personal and Citadel has no purview for review on a personal device.
So yeah, if a hard look is performed, nothing untoward will be found on any cell phone.
I bet they'll take this very seriously and scrutinise every bit of apparatus with which their employees can contact the outside world without the firm knowing - not looking for unauthorised dealing but for evidence of who might be preparing to blow the whistle to the SEC.