Just adding weak attribute adds zero code though, if unused, and it is a one-liner.
Not worried on the reboot case, that's OK. It's the case of where new firmware upload could be faulty...
I'm also thinking another use case as well, like UHS-3, where if you have open files on a USB storage device, and writing is going on, that you could close the file gracefully... e.g. logfile. Would be useful as well with SDcard too.
I can think of dozens of reasons to do this.
instead of overriding the function (and without looking at the core to duplicate the other code you will use in your new one), i think its better to have a separate blank weak function that is added to it at the top of the current function, so when the core runs thru it it runs your code before the core ones, then you wouldnt need to keep track of the core code in your function when you have a blank one to play with