No.
"The genius of Newton allowed him..." would presumably be acceptable to anyone who thought that the original was ungrammatical; it is difficult to justify why one should be correct and the other not.
"Newton's genius allowed Newton..." seems awkward. One asks "Why not use a pronoun?"
Of course ambiguity can arise if one is not careful. "Newton's father encouraged him to study Latin" is not ambiguous, but "Newton's father said he was good at Latin" is.