Again, there's nothing substantial. You're making a link between Elliot, his crime, and Allsafe, but to the uninitiated, all they're looking at is a hacker who hacked people's private information to be used as blackmail, and a crime involved where a conglomerate lost access to its data. It's a huge logical leap for Dom without evidence to showcase.
There's nothing that connects him to the Raspberry Pi in Steel Mountain (there's Bill's testimony to the FBI judging by Elliot's nickname Sam Sepiol, but I'm talking physical evidence), nothing that connects him to the malware used to encrypt ECorp's data. Not to mention, Fsociety made that a lot more difficult now that all their computers are burnt to a crisp. This is why I think Dom is showing Darlene that they know, but she's exploiting Darlene's fears and hoping that she'll crack and corroborate what's on the board.