Let me say there are too many uninformed and uncircumstantial opinions in this thread, starting from the OP. The major flaw of this thread is that the OP pretends to have explained both point of views on the matter of safe or not totally safe personal claims, however it does not. There is no clear explanation as to what personal claims are intended to be and the purpouse they should serve in the game, and why they should be safe from other players. The wiki also does not help in this regard. Without having this clear how can we have any informed opinion on the matter?
I will give my opinion on how I envision personal claims should be, starting from the only certainty I have about them, which is their name. Their purpouse in the game would be to let the lone player have a safe harbour to store their beloginings, since it is obvious that a lone player would not be able to defend them in any other way. However, in my opinion a lone player in this game would only be a player excellent at role playing or a player that does not yet know what they are doing and that would soon either quit the game or join their efforts in a community. But I digress... keeping in mind the above, I would have the personal claim work like this:
1- yes, they would be 100% safe during their existance. This is because a lone player stands no chance against organized groups, and no matter how hard and long and boring you make destructing a personal claim, if this was the case then they would be completely pointless. You could as well petition for their removal. But they could (but need not) be removed by a guild leader should they come to fall in the land radius of a guild claim.
2- a personal claim would be just that: personal. This means no management of accesses or "diplomacy" is possible, only the owner can do anything in it.
3- a character owning a personal claim cannot join a guild, order, or whatever player organization that is concerned with land ownership. They can live in the lands of a guild with their claim, if allowed to, but not be fully part of it. This is to prevent the exploits that have already been covered in the thread, plus all the others that have not because we could not even imagine them.
4- the maintenance would not be costly, however the radius should be fixed, and reasonably small, something like 10 of radius. A single character could barely make use even of that few land, anyways.
5- regardless of its maintenance level, the claim would be destroyed by the system in a maintenance cycle if there is no update in the maintenance status for over 30 RL days, or another reasonable amount of time that would define a player as active in the game or not. This is necessary because if the maintenance cost is low it would be too easy to pay maintenance for one year and quit the game for whatever reason (for example because playing this game solo is a bad choice) a week later, leaving some land claim that none can remove without a guild claim covering it.
Alternatively you could make it costly to maintain, but this would again be against the purpouse of a personal claim. In my opinion it should be something easy to create and maintain for the single player, but that gives no advantages beyond the character itself. If personal claims could be removed by player organizations beyond their claimed land, if they would be hard to maintain, then what would be their purpouse? Why feature a game element that could be potentially exploited and that on the other hand does not give the proper tools to the honest players to play with?
When you think up a feature you must start from its purpouse and convenience, and then find the means to prevent it can be exploited. It is my opinion that save some exceptions, in this thread only the former has been done and that is because, I believe, pretty much none that posted has any intention to play their characters solo, myself included. However we must still maintain a neutral perspective when it comes to discuss play styles.
I am also of the firm opinion that a player or a player organization should only claim (with words, a.k.a. role play) to own what they in fact own. No childish BS like "this clay pit is ours because our claim is in the vicinity". We have enough of this BS in games that don't feature land ownership. This game features it, which means anyone should only own what they truly own, period. Arguments like "I should be able to control the land I own and also its surroundings if my sword is big enough" are pretty moot. Personal claims cannot pose a threat to resource claims for guilds, because a guild whose land expands over such a claim can remove it. If your guild cannot manage to include that particular piece of land in their claim, it is YOUR GUILD's problem, and it must not become John the Hermit's problem only because you are a couple dozeen well armed bullys.
Likewise, the guild claim that is near your guild and is hindering your expansion dreams, cannot be removed simply with your own expansion, it will require either diplomacy or war. This is a system that is fair for everyone as it does not stop anyone to obtain what they aim for, if they work for it.