Por que Ron de repente reavivou o medo de dizer o nome de Voldemort em As Relíquias da Morte?

A partir do seu quinto ano, Ron se viu na companhia de pessoas (a Ordem da Fênix), que não teve problemas com a palavra-V. De repente, não apenas Harry, mas todo mundo ao redor de Ron estava usando o nome de Voldemort:

_{“How can he think that?” said Harry angrily. “How can he think Dumbledore would just make it all up — that I’d make it all up?” “Because accepting that Voldemort’s back would mean trouble like the Ministry hasn’t had to cope with for nearly fourteen years,” said Sirius bitterly. “Fudge just can’t bring himself to face it. It’s so much more comfortable to convince himself Dumbledore’s lying to destabilize him.” “You see the problem,” said Lupin. “While the Ministry insists there is nothing to fear from Voldemort, it’s hard to convince people he’s back, especially as they really don’t want to believe it in the first place. ~OoTP, Chapter 5: The Order of the Phoenix (emhpasis mine)}

e assim por diante, os membros da Ordem seguindo o conselho de Dumbledore se livraram do tabu e estavam usando o nome de Voldemort livremente. No sexto livro, Fred e George até transformaram o tabu num slogan encorpado (U-no-poo). Ron se identificou com esse grupo e adotou o comportamento deles. Talvez ele fosse um pouco mais lento do que Hermione nisso, mas então ele tinha mais bagagem cultural para se livrar.

Mas após a queda do Ministério da Magia eles estavam fugindo, isolados do grupo e perseguidos. Gradualmente, os medos de Ron ressurgiram. Eles foram localizados por Comensais da Morte quase imediatamente, e Hermione não tinha explicação lógica de como isso aconteceu:

_{“But how did they find us?” Hermione asked, looking from one inert man to the other. “How did they know where we were?” She turned to Harry. “You — you don’t think you’ve still got your Trace on you, do you, Harry?” “He can’t have,” said Ron. “The Trace breaks at seventeen, that’s Wizarding law, you can’t put it on an adult.” “As far as you know,” said Hermione. “What if the Death Eaters have found a way to put it on a seventeen-year-old?” “But Harry hasn’t been near a Death Eater in the last twenty-four hours. Who’s supposed to have put a Trace back on him?” Hermione did not reply. ~DH Chapter 8: A Place to Hide}

Como @Adamant menciona em seu comentário, Ron intuitivamente ¹ agarrou a solução:

_{“I’m sorry,” Ron said, moaning a little as he raised himself to look at them, “but it feels like a—a jinx or something. Can’t we call him You-Know-Who— please?” ~DH, Chapter 14: The Thief}

Ron não convenceu seus amigos. A partir da reação deles, parece que eles decidiram entrar e não perturbá-lo quando ele estava se recuperando de sua lesão:

_{“Dumbledore said fear of a name —” began Harry. “In case you hadn’t noticed, mate, calling You-Know-Who by his name didn’t do Dumbledore much good in the end,” Ron snapped back. “Just — just show You-Know-Who some respect, will you?” “Respect?” Harry repeated, but Hermione shot him a warning look; apparently he was not to argue with Ron while the latter was in such a weakened condition.~(ibid)}

eles atribuem o comportamento de Ron à mera superstição sem qualquer base lógica, não diferente de quando Ron se assustou com o Grim em seu terceiro ano:

_{Ron looked at Hermione as though she had gone mad. “Hermione, if Harry’s seen a Grim, that’s — that’s bad,” he said. “My — my uncle Bilius saw one and — and he died twenty-four hours later!” “Coincidence,” said Hermione airily, pouring herself some pumpkin juice. “You don’t know what you’re talking about!” said Ron, starting to get angry. “Grims scare the living daylights out of most wizards!” “There you are, then,” said Hermione in a superior tone. “They see the Grim and die of fright. The Grim’s not an omen, it’s the cause of death! And Harry’s still with us because he’s not stupid enough to see one and think, right, well, I’d better kick the bucket then!” "[...]" “I think Divination seems very woolly,” she said, searching for her page. “A lot of guesswork, if you ask me.” “There was nothing woolly about the Grim in that cup!” said Ron hotly. “You didn’t seem quite so confident when you were telling Harry it was a sheep,” said Hermione coolly. “Professor Trelawney said you didn’t have the right aura! You just don’t like being bad at something for a change!” ~PoA, Chapter 6: Talons and Tea Leaves}

Mais tarde, Ron verifica que seu palpite sobre o nome de Voldemort ser azarado estava certo:

“but the name’s been jinxed, Harry, that’s how they track people! Using his name breaks protective enchantments, it causes some kind of magical disturbance — it’s how they found us in Tottenham Court Road!” “Because we used his name?” “Exactly! You’ve got to give them credit, it makes sense. It was only people who were serious about standing up to him, like Dumbledore, who ever dared use it. Now they’ve put a Taboo on it, anyone who says it is trackable — quick-and-easy way to find Order members! They nearly got Kingsley —” _{~DH, Chapter 20: Xenophilius Lovegood}

_{1. Reconhecimento inconsciente de padrões e capacidade de entender algo instintivamente ( Wikipedia )}