Not incorrect, but again, I find that open is where the game shines where everything can happen. Personally I believe that getting a good and solid crime/punishment/consequences system build into the game that makes lore wise sense (for example high security having...high security) could make people return to open, because people that grief would eventually not be able to easily be in the systems they would want to cause grief in, their own actions would get them excluded. Though yes I know a lot of games are seemingly afraid of punishing players, so there's little reason to believe that Elite would be different on that part, though I hope it will be and think it will be from what Elite has shown me so far, but yeah I can definitely understand people going "Just give us a PvE mode"
Griefers / gankers will be there ad mortem defecatam, no matter the crime and punishment system, because for them being fined / having bounty on their head is not a problem. Being destroyed by other ships (PC or NPC ones) is not a problem. They do not need a high end combat ship to hunt down small vessels typically used by new players (Sidewinder, Adder, Hauler). They don't need a high end combat ships to hunt down heavier trading vessels (T6 or T7). Viper (c.a. 150k) with default loadout is more than enough for that. Give me T6 in a good area and 30 minutes and I can get 5-10 Vipers or 5 Cobras, and just self destruct each of them without rebuying. Which means that with insurance I will be able to afford to burn through many, many more ships. What's more, I can keep separate, spanking clean account as the piggy bank, and another one, not so clean, for griefing. If I have more funds and some better combat ship at my disposal, it's just easier and quicker to take down either weak opponents or unsuspecting targets in PVE only private group without taking too much damage (if any) myself... Kill, refuel / reload, kill again. Bounties are cheap, ammo is cheap, fuel is cheap. If bounties get higher, I can happily use them with a few buddies to print credits for griefing.
There are other PVP options out there (CZ, CQC for example) where players can test their skills against other players. But the essence of griefing is not testing your skills against other players, it is causing as much damage and chaos as possible to other players and show how helpless FD, support and community are when it comes to tackling the problem. Somebody reports me as a griefer? Well, killing players is part of the game, isn't it? It's a cutthroat galaxy which allows me to attack other vessels wherever and whenever I wish to do so, I'm not doing anything against the rules, I'm not breaking EULA and it's not that easy to punish me for being an a***hole.
Besides I can find several reasons to excuse myself, blame the victim and get out of trouble quickly. In short, griefing is a personality issue, not a function of the game design.
Frontier would have to very precisely define what behaviour is allowed in this game (and they are not going to do that, after all they advertise it as a game where you choose the way you play yourself) and permaban everybody who breaks the rules (which I think they won't do). Or make sure they offer an option where no PVP is allowed without explicit consent of both sides. Otherwise this issue will be coming back to them and cost them time and money.
As for players who do not play in Open, you can forget that changes to the crime and punishment systems will bring them back to open. Players choose to stay in Solo or go to private PVE groups mostly because they have preference for those game modes / gameplay styles. I'll give you an example: you can offer somebody the best single malt, if they don't drink alcohol on principle, they are not going to be interested in how log it was sitting in a barrel and how amazing it is. Or: if somebody likes jazz only, you do not force them to listen to R&B. The Open mode is there. If anyone wants to play in Open, they will do so.
That is precisely why people who have experience developing multiplayer games with PVE gameplay pay attention to separating PVP and PVE in one or another way. By having separate PVP instances, by making sure that players of higher level can't attack players of lower level. Because bringing PVP and PVE gameplay in one place is simply never going to work, no matter how fair and just the mechanics systems in place are.