If you can kill people then the HUB will be a ghost town filled with PVP dicks who kill newbies.
If you make people unkillable at the HUB then the guards can kill dicks.
When people could be killed there wasn't a massive problem with people killing newbies at the Hub. People blowing themselves up from time to time is annoying but wasn't/isn't there now a thing where the guards can detect active bombs on someone and kill them? What was wrong with that?
I would rather deal with people who might blow me up then assholes who like to stand in doorways all day. It will only be a matter of time before one asshole finds some friends and then every door will be blocked.
You block a door you get killed. You're new and get killed in the cross fire... lesson learned. Some asshole blows you up.. lesson learned. School of hard knocks.
Also isn't one of the up coming changes a barter grounds closer to the Hub? If so newbies can go there and be free from bombers and thieves. Put a merchant or two there, selling low level items and not a lot of caps.
Could also have it so getting killed by the guards doesn't make your bad deeds go unremembered. You kill people or cause enough troubles there.. get killed. If you step foot in the town again before 24 or 48 hours real time you will get shot again. If you get killed in the cross fire you won't get in shit. I am not sure if something like that can be programmed, something that lets the guards know the good from the bad, but hey it's an idea.