This is a dangerous road to travel, as the exact same thing can be said about most other tools that can be abused. Knee-jerk reactions like this are shortsightedly ignorant and do nothing to mitigate actual harm being done.
Flipper zero’s capability is not based on some super advanced technology, it can be replicated. Banning stuff is an easy way to cover the problem up but instead of actually fixing anything, it is sent out of view of the mainstream and into shallow obscurity.
People who steal cars already break the law, breaking an extra one by possessing the tool is not going to be a deterrent. Researchers and security auditors who stay above board will no longer have access to this tool if they expect to exist in a professional capacity, effectively kneecapping their ability as our allies to help us create more secure systems.