I have successfully reproduced this issue and I am working on a fix. At the moment it appears to be a problem within Galacticraft itself, unrelated to the modpack. I'm not sure if your world can be recovered but I will do my best to see that it is. For now, if you create any new worlds, stay away from those two dimensions.
I agree with you on this but it's not my decision to make. While pvp isn't all that common on the server, ICBM warfare has actually occurred. Players generally like to play it safe and make nice with each other to insure their hard work isn't destroyed, but at present, there are no rules against pvp and griefing outside of protected regions.