Sorry about the delayed reply----I have been busy. Well, my reply is basically made up of my other posts on the topic. Feel free to debate on this Valandil-it is a topic we disagree on.
The decision to appoint Eärnil II was a logical political one. Why? Well, even though
Isildur held himself to be High-King of
Arnor and
Gondor we don't know if his descendants continued this. Certainly after Earendur and the ensuing feudal war within 'Arnor', the issue of High-Kingship in terms of Gondor would have been pretty much forgotten. No Arnorian King is said to claim the throne a Gondor when any of the King's didn't have a child. (Tarannon Falastur, Narmacil or when Telemnar I and his children perished in the Great Plague. Or even in the Kin-strife, though at this time the
Dunedain of Gondor were divided with the supporters of Eldacar and the confederation of various descendants of Anarion, who removed to
Umbar. Castamir was the chief of these and
the one who took the Kingship from Eldacar.
It seems that Ondoher was attempting to secure better relations between Arnor and Gondor, hence his marrying of his daughter, Firiel to Arvedui, the King of Arthedain. But Ondoher and his sons were slain in the Battle with the Wainraiders. Eärnil in effect saved Gondor after first defeating the Southern Force and then routing the Northern one when they were feasting. He was a hero.
We then get two people claiming the kingship. Eärnil, the captain of Gondor, has just saved Gondor, descended from Meneldil, who Isildur relinquished the
realm to (though he still claimed over-lordship over the realm), known and loved by the Dunedain of Gondor, and descended from the male line, from Arciryas, brother of Narmacil II. Descendance from the male line is important in Gondor. In
Numenor, Tar-Aldarion changed the laws of succession to get back at his wife, so Ancalime could become Queen. Of course unlike any male heirs to the throne, the female ones could refuse the sceptre, as did the sisters of Tar-Anarion. But in M-E, where war was ravaged, this law seems to have been rejected and passed over. Women weren't good war time rulers. So descendent from the female line seems to have been rejected, thus one of Arvedui's claims, that he is married to the last child of Ondoher cannot be seen as being a legitimate claim. Tarannon Falastur was succeeded by his nephew of his brother, Narmacil I by his younger brother and Telemnar by the son of his brother.
The people of Gondor at that time thought little of Arthedain too. Plus the claim of Earnil was universally accepted and supported. Plus the fact that Pelendur, Earnil's steward, was a great supporter of the claim of Earnil shows there may have been some selfish elements to the rejection of the claim of Arvedui, maybe he would have less power/influnece under Arvedui or maybe it was because he was close friends with Earnil. This was a few hundred years before the death of Ondoher. (Of course the house of
Stewards had begun with
Hurin, steward of Minardil, who was slain by the Corsairs and it was in his sons time, King Telemnar that the Great Plague came and Tarondor removed to
Minas Anor (Tirith).)
The choice to appoint Earnil was the more sensible one. There was no 'spritual' reason behind it, it was simple politics.
Taken from
The Gondorian Council Worthy?
The question of the Salic law in
Middle-Earth is an ambiguous one.
Númenórean laws state that somebody can come to king/queenship through the female line, after the whole Aldarion incident. But the law went through a great deal of change of the years.
Elendil and co. were conservatives-and descendants of the female line from
Elros. So it would be kind of ironic if they said "no descendants from the female line" straight away. It would have been silly. The whole Salic law thingy, which was brought to the fore after the death of Ondoher and his sons, and Arvedui, pressed his claim, as the descendant of Isildur, the "high king" of Arnor and Gondor, and eldest son of Elendil, the first king, as well as being the husband of Ondoher's only child, Fíriel. The Gondorian council rejected his claim, in the favour of the war captain Eärnil-a member of the royal family, and the saviour of Gondor. They claimed that in a time of war, salic law should be allowed, and that it was allowed in
Númenór because Númenór was in a state of perpetual peace. Any continuation of the salic law would take place when a state of peace existed. Plus Isildur's claim of high-kingship could not be re-claimed so many years after his death, and it made more sense for the popular Eärnil to be king-they wanted to avoid any dissonances and a possible civil war. Any civil war would have left Gondor very weak. So a descendant of Meneldil was needed, and Eärnil fitted the bill. Sorry for digressing.
Taken from
Hobbit population and the age of men
You say you are interested in Arnor-perhaps you will be interested in the following;
The Civil Wars of the Dunedain
Differences Between Arnor and Gondor
The Enigmatic House of Hurin