The risk is real because as we all know, supervision is an area that can never be perfect as it lacks the resources to see everything, meaning that accidents are always possible. What I would call “false” risks include the argument that conflicts of interest might arise between the different central bank functions.
Could a central banks’ concern for the health of banks jeopardise its price stability objective? Would a central bank create an environment with low interest rates with the aim of supporting the banking sector’s health? I would argue that the answer to these questions is no. The ECB will have clear separate and hierarchical mandates that places price stability separate from other concerns.