Propranolol hinders short-term memory in some patients. Surely, in high enough doses and in the wrong hands, propranolol can alter people's minds when memories are skewered and new memories are put in their place. When new drugs hit the market and their effects are not entirely known even after clinical trials, there is no telling what propranolol can do in high enough doses.
Any chemical, compound, or new technology can be misused, but there is no indication that Propranolol will be misused by authorities or by others in any way that isn't already available through other means. The potential for misuse of anything is not a reason for them to be banned or controlled - houses are full of potentially harmful materials.