From what I read in the section on the "Statute," the reason Finwe never
returned was solely because only one of the two from a dissolved marriage
*could* return. (This topic is presented in great detail and argued at length
amongst the Valar, and I'm not going to try to summarize it.)
Finwe wanted to marry again when it was clear that Miriel would not return.
Miriel, when asked, forfeited her right to return saying that she has no desire
to ever again join the Living. She changed her mind after Finwe showed up
(after Morgoth kills him) and filled her in on all that she had missed. It was
then that she expressed regret for deciding earlier to give up her right to
return among the Living. Finwe, pitying her, volunteers to remain forever in
Mandos so that Miriel can return. The horrible thing is that she does return
but is again unhappy and returns to Vaire, thus making Finwe's sacrifice vain.
Anyway - I did not get the impression anywhere in that essay that Mandos ever
denied Finwe the right to return. In fact, I never got the impression in any of
Tolkien's work that Finwe was held to blame for anything related to Feanor's
actions. The extent of Finwe's involvement was to accompany his son in his
exile at
Formenos.
-----------------------------
Now news came to Hithlum that Dorthonion was lost and the sons of Finarfin overthrown, and that the sons of Feanor were driven from their land. Then Fingolfin beheld (as it seemed to him) the utter ruin of the Noldor, and the defeat beyond redress of all their houses; and filled with wrath and despair he mounted upon Rochallor his great horse and rode forth alone, and none might restrain him. He passed over Dor-nu-Fauglith like a wind amid the dust, and all that beheld his onset fled in amaze, thinking that Orome himself was come: for a great madness of rage was upon him, so that his eyes shone like the eyes of the Valar. Thus he came alone to Angband's gates, and he sounded his horn, and smote once more upon the brazen doors, and challenged Morgoth to come forth to single combat. And Morgoth came.
