Lol on what grounds could they be held liable? Arguably, people who
worked at FTX didn't all know SBF loaned out customer deposits. Even SBF himself claims to not have realized the extent of it. The truth of SBF's claims should be determined by an investigation, however I don't see cause to go after these celebrities. They were paid to make general statements by the company, they didn't sign financial statements.
If there is some indication they knew it was a scam, then sure go after them. But you can't just seize everyone's emails because you think there's a chance they were involved. You need probable cause.