A reasonable person would interpret the words as a promise of employment, and this is enough to make it true that McKittrick had reason to know that Embry attached a different meaning to his words than he himself did.
He may not have realized he had the reason; he may not have reflected on it, or drawn any conclusions from it, but he had the reason nonetheless. Such situations are familiar to all teachers and students.
In legal education, it may happen that a student knows the legal rule, and understands all the relevant facts of the fact pattern to which the student has been asked to apply the rule. But the student may fail to draw the correct conclusion even though he or she has, and understands, all the reasons--the rule and the facts--that lead to that conclusion.