Speeches: Are They Copy?
Short answer: No. Speeches are speeches. And when someone writes a speech, they are acting as a speechwriter, not a copywriter. Speeches are not directly a form of branding, but rather a form of rhetoric.
Long answer: Speeches can be considered copy because they focus on persuasion. In normal copy, the emphasis is a product or service, but in speeches, the selling point is either the person delivering the speech or the end-result of their goal.
This may sound contradictory to call speeches copy and then not-copy, but that's the most intriguing thing about speeches: they're this Schrodinger's Writing where they simultaneously seek to persuade, but not sell. The product is your pathos, and while it may sound trite and even insulting to "commodify" a person's integrity, every set thing in this world as value (whether intrinsic or extrinsic).
So why bother with labels to begin with? Speeches are copy and not-copy. Speeches are a mixture of branding, debate, charisma, and logic. And so is copy. That's why I don't balk at lumping speechwriting with sloganeering or direct mail. Just as every human interaction is a form of persuasion, speech is a form of branding, and there's nothing shameful or "dirty" about branding unless the product could be described as such.
And the biggest advantage of hiring a speechwriter? No cliches about taking the road less traveled by or even worse: "I'd like to start with a story..." Public speaking is the most common fear in the US, so don't make it worse with traumatic tropes.