Roms are illegal to put up for download, or to upload them to a publically-accessible web server.
You can personally make a backup of a game you bought and own for personal purposes only. Even if you did buy, and own the game, it's illegal to download a console backup off the internet if you didn't create it yourself.
The 24 hour excuse is bull crap. Emulation websites use that as an excuse to get away from the smaller lawsuits until the big boys go after them (Nintendo, Natsume, whatever).
Some companies don't care, if the game is pretty old and they don't make money off of it anymore, then-on seen as abandonware, or maybe they are just blind, old-bats that don't know how to navigate a rom website through all the popups to find the illegal stuff.
