This move is really akin to banning a Hello Kitty Lockpick set after discovering most locks are snake oil, instead of demanding reasonably secure locks be sold instead.
Having a simple nice form-factor for something that can do under 1GHz am/fm, BTLE, IR, dallas 1wire, and pinouts for expansion in a simple smaller-than-cellphone device is pretty sweet.
Sure, script kiddies will be script kiddies. And sure, they shouldn't do bad shit, but they will. It's also your responsibility to run reasonably secure stuff.
And no, the FCC won't help you. You're not big money like cell, digital TV, or avionics.
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EDIT cause of too many comments bullshit:
This conversation chain is sure sounding like https://news.ycombinator.com/item?id=9224 , the whole "dropbox is inferior to FTP". We all know how that worked out.
Having done actual RF, electronic, software, and encasement design - it's nowhere as simple as "cobble it and 3d print a case and done". If it was, we would have seen a Flipper Zero like thing ages ago.
Prove me wrong. If it's that simple, point me to a blog or github that you execute on all the assets within a week. (because it aint)
For the kind of person who does that putting it in a 'ok' case is not that much work...
This is likely @pierat's point: sure, it's possible, but your diy version will be objectively worse in a variety of ways while also taking you a pretty long time to put together.
I've already done basically this level of stuff for my own custom bluetooth mechanical keyboard projects (a keyboard is larger overall, for obvious reasons, but the space beneath it where you can fit electronics is quite limited) and I've made a few resin cases for other electronic hobby projects. The software side of the Flipper is much more time investment but still something I could do if I was fully motivated and had no other obligations getting in the way. Or I would just cheat and specifically use the same STM32WB55 microcontroller and re-use the existing Flipper's firmware directly. Designing a case and a PCB for something of the Flipper's complexity is really not that hard. A day or two each.
Honestly, I find the Flipper's case to be pretty poorly designed for actual usability, it's mostly just directly exposing hardware externally in as small of a space they could get away with, it's a complete pocket brick otherwise. It's a striking visual design with the angles but actually kind of terrible at slipping in and out of your pocket and is awkward and clumsy to use one handed or subtly. Cell phones (at least up until very recently) carried similar radios, IR blaster, SD slots and ports in much better and smaller form factors, and are so normalized in public use that it might have flown under the radar both in consumer's eyes and regulator attention if it wasn't actually so visually distinctive.
If you have the skills to build a GHz SDR from components, and write some C to attack a car starter, you probably have better ways to make $2k than stealing a car. Evilduck obviously has better things to do.
Releasing a Hello Kitty SDR makes these attacks practical for a much less capable population who actually will go steal a car.
I can testify that the bike theft industry in Toronto was driven by one mad genius for a generation. Igor Kenk was like a spiderman villain. He ran a vertically integrated business: providing specialized tools for cracking locks; training on their use; and then providing coke/crack directly for stolen bikes eliminating the cash-handling risks of the business. Just a total mad Chad.
If Flipper enables another guy like Kenk to build an empire of idiot car thieves, I can understand the butt-hurt.