.......... Federal law allows the transport of weapons in vessels if they are unloaded, rendered temporarily inoperable or are packed, cased or stored in a manner that will prevent their ready use. ....................
I don't know if this is correct or not so I won't comment on that point, but if you are carrying a weapon and are in compliance with that law, it's going to be useless for "protection".
You can't ask the bad guy to wait while you retrieve your gun and load it.
Even if federal law seems to allow you to transport a weapon regardless of state or local law, it doesn't protect you if you actually use the weapon on a human. In some states, you are within your rights to shoot someone who threatens you. In other states, you are obligated to attempt to hide or escape. You're not likely to have time to look it up.