Nephi is much more clear in his prophecy of the Charles Anthon encounter than is Isa 29:11-12. Look at the following passage, the Lord God shall say unto him (Joseph Smith) to whom he shall deliver the book: Take these words which are not sealed and deliver them to another (Martin Harris), that he may show them unto the learned (Charles Anthon), saying: Read this, I pray thee. And the learned shall say: Bring hither the book, and I will read them. Martin Harris recorded the following history:
"I went to the city of New York, and presented the characters which had been translated, with the translation thereof, to Professor Charles Anthon, a gentleman celebrated for his literary attainments. Professor Anthon stated that the translation was correct, more so than any he had before seen translated from the Egyptian. I then showed him those which were not yet translated, and he said that they were Egyptian, Chaldaic, Assyric, and Arabic; and he said they were true characters. He gave me a certificate, certifying to the people of Palmyra that they were true characters, and that the translation of such of them as had been translated was also correct. I took the certificate and put it into my pocket, and was just leaving the house, when Mr. Anthon called me back, and asked me how the young man found out that there were gold plates in the place where he found them. I answered that an angel of God had revealed it unto him.
"He then said to me, 'Let me see that certificate.' I accordingly took it out of my pocket and gave it to him, when he took it and tore it to pieces, saying, that there was no such thing now as ministering of angels, and that if I would bring the plates to him, he would translate them. I informed him that part of the plates were sealed, and that I was forbidden to bring them. He replied, 'I cannot read a sealed book.' I left him and went to Dr. Mitchell, who sanctioned what Professor Anthon had said respecting both the characters and the translation." (History of the Church, vol. 1, p. 20)
Neal A. Maxwell
"This is not solely a reference to professor Anthon, since the plural pronoun they is used (2 Nephi 27:20). The reference suggests a mind-set of most of the learned of the world, who by and large, do not take the Book of Mormon seriously. Even when they read it, they do not really read it, except with a mind-set which excludes miracles, including the miracle of the book's coming forth by the 'gift and power of God.'" (First Nephi, The Doctrinal Foundation, BYU Religious Studies center, p. 9 as taken from Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 157)