I hope that you see that this is for your protection. If you can open a
suspended computer and then gain access without a password then anyone can
mess with your personal files. That is why it is set as a default to use
password protection. I have turned this off on my desktop computer because
it does not leave my house where I trust everybody, but I have kept it on my
netbook because I carry it places where I do not trust everyone.

To fix your problem you likely need to edit gconf since it is by-passing
built in default settings.

Press Alt-F2. Type gconf-editor go to the section
/apps/gnome-power-manager/lock.