If switching from a weaker bank of batteries to a fully
charged bank, then the armature coil inside alternator cannot
discharge fast enough. Load dump results.

Both SAE J1455 and ISO 7637-1 defined load dump for 12 V
automotive alternators as up to 270 volts and energy up to 50
joules. Still think alternator can safely switch batteries
when fully charging? What happens to 12 volt radios when
confronted with something less than 270 volts?

Provides were product lines for protection from load dump.
Does every electronic device onboard have such internal
protection (... or why marine stuff may cost more)?

Jere Lull wrote:
...
But any quality switch I've dealt with (some 30 years old) was
make-before-break, a non-issue. Of course the engine loads down
heavily when tasked with charging the weaker bank, but that's
self-correcting.