It's probably more of a tradeoff.
This longer delay won't prompt hectic headlines about users angry about random reboot, it is long enought so federal agencies won't publicly react and plea Trump for their backdoor again, and it is a low profile update that won't necessarily be noticed beside tech circles thus "small fry" bad actors won't know how to correctly cover their back.
A user hostile design would have been to never implement it in the first place. It's basically Apple's signature to choose generic default value and don't bother the user (for the better and sometimes the worse).