Yeah, I'm not saying that PvP deaths are all that common, but I think this is mostly due to players learning to be paranoid rather than any lack of griefers. The problem with newb killing is that it tends to be like plane crashes - lots of people die at once. We have almost every incarnation of Brodgar as an example, and there'd be lots of other examples if forums didn't get nuked

Anyway, like with plane crashes, the problem is the perception that this creates. And the fact that the best way to avoid this is dispersing, which makes H&H feel like singleplayer.
Now, getting players to not engage in newb massacres is a noble goal, but I think it's an unachievable one. I can't really imagine any mechanics that would do that that aren't prone to exploits and don't severely hinder killing when there's legit reasons to do it (escalating disputes). With my proposed system you can still remove
kebab nuisances from your corner of the world, you just need to invest more effort and kill their realm claim first. I don't think it's unfair to require a day or two of investment to kill characters with months of investment in them. And it lets you kill troll alts that people spawn to block gates and shit, as long as you're the realm holder / have justice permissions. So I'd say this is a decent compromise between the non-permadeath and permadeath camps.
What this shouldn't do is make opting out of PvP an optimal choice. Death protection means the realms are gonna be crowded, so going out in the wilderness to forage and hunt should be a lot more profitable than staying safe. It just moves the gamble further out from your walls, and replaces the risk of leaving the walls with a lesser one. Escalating risks vs escalating profits is a staple in gaming for a good reason, and it's frequently used in games with high death penalty, such as roguelikes (do I delve deeper? / do I raid that Njerpez camp?) and MMOs (system security in EVE). Lessening the potential cost of just leaving your walls should if anything make the game more bloodline oriented - as it is now people play a clan rather than a bloodline, with farmers/crafters that never leave the wall, and there'd be less need for that if your crafter just gets disabled for a week or two rather than completely lost. And when people don't need separate characters for just leaving the walls, they're likely to get lazy and just use one character even for leaving the realm borders.
The fluff of getting ported to hearth is kinda lame, sure. I guess you could draw Valkyries descending to snatch you from jaws of death and return you home. It doesn't really make sense, but games rape mythology all the time, you should try it too, it's probably fun

But seriously, I guess you could make it so you simply can't hit a downed character, but the newbies wouldn't know that and they'd just get up repeatedly instead of logging out or porting home :/ Making it a chance to not die though isn't gonna work, people will just keep wailing on a "dead" character for 20 minutes or so to be perfectly sure.