Ok, you are making several assumptions here, so let me address them one by one:
> Swiss Army Knife does not provide any functionality that can't be provided by any other basic household object
That is true, but you don’t go around carrying all these individual tools in your pocket, do you? That’s the whole point of it, portability. The same goes for the flipper zero, you have a bunch of useful tools that you can buy off the shelf yourself, but they are not convenient to carry with you all the time.
> Flipper Zero on the other hand is a toy with no/little actual utility
Who says that? Anything can be a useful utility in the right time and in the right hands for a specific purpose. Maybe one tool is useless to you, while useful to another.
Some people might use it to store hundreds of keyfobs, so instead of carrying all the hardware for each, they can use one device instead. Others might use it to control their home devices, either the IR remotes, or other smart devices, and instead of having 15 remotes (I personally do), they can use one device. Some other person might use it to monitor their TPMS in the tires, others to monitor a serial GPIO port, and so on. All these are not only legal, but you can perform all the individual tasks with a “collection” of tools, like reading the serial GPIO, you can buy a dongle for $10, IR remote? You can use some android devices, etc. However, with flipper zero, it’s all-in-one.
> that enables users to perform illegal/dangerous tasks
Just like any other tool out there, any tool can be repurposed to do illegal tasks, either the tools I mentioned or any other ones, including your smartphone, you can load a custom OS (say Kali linux) and perform illegal tasks, do you ban smartphones? Do you ban Kali linux? No, but if someone is found guilty of performing these tasks, you prosecute them. The same goes for anything, your car, can be used for everyday tasks, or even illegal stuff.
> like steal cars that would not otherwise be possible except via less accessible/illegal means.
Flipper zero can’t steal a car, it’s too damn weak for that job. If you are too concerned about that, will you ban ALL SDR in the market too? Because if someone has a bad intention, and you banned flipper zero, they will go and buy BladeRF SDR for example (that’s very accessible and legal to buy), far more superior than flipper and proceed to commit whatever they want. How’s that flipper zero ban working to prevent the crime? Not at all.