I will quote/repeat, for emphasis, the “taken as evidence” part. Every firearm, at the immediate scene of a shooting incident, is probably going to be examined, for evidence of having been fired. This is a minimum, and may well involve all such weapons being taken “downtown.” Weapons that are deemed to require ballistics testing will be downtown, for some amount of time. Weapons that are held as evidence may be downtown for years, and/or until the case has worked its way through the court system.
If I lived in an oppressive state/jurisdiction, I might well want to have a spare weapon (or two, or three,) stored in a VERY secure off-site location. (Remember, curious kids WILL find EVERYTHING.) Even a not-quite-so-oppressive jurisdiction might want to take, into evidence, EVERY weapon in the home, especially in the event of a home-defense incident.
Edited to add: I do not want to take this thread down any rabbit holes, regarding evidence, legal stuff, and such. This is just to further emphasize why a mere one or two handguns will just not do, for me.