Time to Stir up Trouble
The Syndicate is a crime organization lead by Jimmy and Johnson when they had officially left Hydra a couple of decades earlier. Even so, both of them are allowed to keep their memories, experiences and social connections that they managed to form with other members.
There is actually no need to erase their memories and severe their connections with Hydra and any of my organizations, public and private. This extends to the members of those organizations as well.
It is better not to, considering that their knowledges and experiences assure their undying loyalty.
In addition, it will also make absorbing their assets or dismantling their organization much smoother in the future. And yes, I will have to dismantle their syndicate eventually, or at least, transforming the organization into something more legal.
Legality is subjective, as laws are created by people and not necessarily for the people.