Is the preacher's claim that Uthman's Mus'haf contains spelling errors and that Uthman's scribes wrote out of laziness true?

It is not permissible to say that what the Companions wrote of the Qur'an contains errors or was due to negligence, because revelation approved their ijtihad (definition) (independent reasoning), and the Qur'anic script has received the consensus of the Ummah since the era of the Rightly Guided Caliphs. The Qur'anic script has differed from spelling rules in some words to accommodate a Qur'anic recitation or for other reasons, and the Companions had more knowledge of the language and the Qur'an than those who laid down the spelling rules. The imams of the madhhabs (schools of thought) have issued fatwas (religious edicts) that it is obligatory to follow the Uthmani script and it is not permissible to deem it incorrect for violating spelling rules.