After owning classic cars I know how quickly rust can take over and also how hard it is to remove. Its like a virus!
Thats why I wasted no time getting this work done.
Also I can't help myself... I have to tinker, fix and build things!
I would be concerned however about simply "touching up" with paint over the rust. I would imagine that would just seal it in and alow it to continue.
Your best bet is to sand it back then touch it up.