Não seria perigoso, apenas desagradável. De Retorno do Rei :
Then Denethor leaped upon the table, and standing there wreathed in fire and smoke he took up the staff of his stewardship that lay at his feet and broke it on his knee. Casting the pieces into the blaze he bowed and laid himself on the table, clasping the palantír with both hands upon his breast. And it was said that ever after, if any man looked in that Stone, unless he had a great strength of will to turn it to other purpose, he saw only two aged hands withering in flame.
Return of the King Book 5 Chapter 7: "The Pyre of Denethor"
Eu interpreto a declaração de Aragorn como significando que olhar para a pedra seria um olhar traumático para um homem queimando vivo .
Para Pippin, que passou um bom tempo com Denethor durante sua estada em Minas Tirith, isso provavelmente seria ainda mais traumático.