Yes the summoning issue was nasty, I'd like to see that mofo banned, BUT is a weak case to be made EULA-based. Afterall, you do have to accept, you do have to be added to a guest list in 1st place etc. Is not like some characters comes and *hack* you and bam, you're left with no peds.
It's not an exploit in terms of bug abuse, but rather griefing. As you mentioned, both guestlists and summons are normal ingame mechanics. But the way it's used causes trouble for normal players. I'm fairly sure that pirates are aware that the summon box gets in the way for normal ingame activities, and that some players press it by mistake. (Unless you have missed it, the summon box pops up in the middle of the screen, and you're very likely to click it by mistake when your intent is to use a non-buttoned weapon at a mob, or if you are in progress of merging stackables between invnentories then the dialog boxes are nearly identical.
Also note that there are players who doesn't speak English well, their native languate might be russian, serbian or some other language the client does't proivide native support for, and to press "ok" (the "green" choice) on a popup that comes up shouldn't lead to you being looted and marooned.
When there was a bug in land areas making them and the land immediately around the revivals pvp, MA sent out a message that abusive pvp could be punished. This was despite the principle "in pvp anything goes".
And, again, I don't Think the protection against going into space by mistake is high enough. Imho there should be a clear protection against entering lootable pvp by mistake even inspace, as there is the needed antitoxic shots to enter lootable pvp planetside.
Summons: YES you can click the box by mistake. Also, the box is rather small so the warning about that there is a cost associated with going back to planet isn't visible, so beginners who Thinks it's cool to get a summon can get themselves stuck at space station.
Quads/VTOLS: Only the pilot/driver gets a clear yes/no option. The passenger gets a warning but might be distracted, lagged or simply doesn't know how to bail out (ie exit vehicle) Before entering space. While in space, the passenger has no option whatsoever to bail out Before entereing lootable pvp - as we know, "T" is disabled and exit ship (using the exit vehicle function) is explicitly disabled. Passenger can disconnect, but if pilot can enter lootable zone in less than 20 seconds passenger will be floating around in lootable space at next logon.
I don't blame the pirates for abusing this. A big part of this thing with beginners getting hauled into space, getting killed robbed and abandoned is because of he lack of safeguards Before entering space that MA has designed. For instance, if the summon box wasn't an obnoxious popup then this wouldn't have been a big thing.
As for bans, if the pirates doesn't abstain voluntarily, then MA must enforce a temporary ban or at least lockdown of the ships involved, until the space UI is made so that this kinds of actions doesn't make peopel who didn't intend to enter space to accidently arrive there.