"A sensible person like you" vs. "a sensible person like yourself"

Both are grammatical. Pronouns like yourself are reflexive pronouns and they have two main uses. One is to ‘reflect’ the action described in the verb back onto the subject, as in ‘I hurt myself’. The other is to emphasise the doer or the recipient of an action, as in ‘I did it myself’. In your example, yourself is used slightly differently in that it’s preceded by a preposition. The effect is to draw greater attention to what the professor, as a sensible person, might be permitted to do.

The reflexive pronoun yourself is the marked form here. To me it suggests that the speaker believes it shows a little more deference than the unmarked you.

And surely you mean surely not surly!