OK, no law says you must use all available resources in an emergency.
Of course every system should be maintained in proper condition. But the OP's question was about the hand brake.
I love how you reminded us that no law says (blah-blah)... I have this mental image of a driver merrily debating the points of the law with the EMT's all the way in to the E-room. :lol: Really, if there's an emergency and I need to do something I wasn't expecting, my thoughts aren't filled with scores of of DOT regs, manufacturer recommendations, etc. What I see is a quick "Hey... That'll work! WOW!"
What I DO like about the Honda system is how it's different from the system I had on my GM trucks. The emergency brake was only a different way of using the same brake shoes that the rear wheels used for normal stopping and while they could slow the truck to a stop eventually if used in a brake failure (and that DID happen to me when I lost the master cylinder) the system was poor at best for holding it in place, especially in reverse. The Honda disc/drum version is solid and gives me more confidence that it'll work as needed - assuming the cable linkage is more reliable over time than the GM parts. They usually rusted solid after 30-50k miles even with regular lubing.