Why can one simply remove the brace and store it separately?
Many of the affected pistols have the "brace" as a permanent fixture. You might have to engage the services of a gunsmith to remove it to ATF's satisfaction.
An AR lower with a standard buffer tube can be easily modified with a plain "tube" buffer tube that can't mount a brace. Swap the tube, discard the brace. It's not that simple with the customer lower/brace on the Honey Badger.