From Ars Technica:
A FBI agent told Shafer the raid stemmed from an incident in February, when Shafer discovered a file transfer protocol server operated by Eaglesoft, a provider of dental practice management software. The FTP server reportedly stored patient data in a way that made it easily accessible to anyone. Shafer contacted DataBreaches.net and asked for help privately notifying the software maker, and once the patient data was secured, the breach notification site published
Based solely on this article it seems the FBI raided the home of Justin Shafer with guns drawn, hand cuffed him and seized all his computers and devices because he exposed a security problem with Eaglesoft.
I have no idea if what Justin did was in any way illegal. I am sure it was embarrassing to Eaglesoft. Whatever the armed raid seems massively excessive to me. Read the article including the comments. Interesting and disturbing.