Maybe you're just wrong about this? I know, crazy, but that kind of stuff does indeed happen. No one is out to get you. The authors refuse to give up a student

Maybe you're just wrong about this? I know, crazy, but that kind of stuff does indeed happen. No one is out to get you. The authors refuse to give up a student because it contradicts their core values as exemplified by several academic predecessors. There's no appeal to authority here -- it's their beliefs, held for presumably many valid reasons. Pointing out that these values constitute a long-standing tradition at Cambridge is not the justification on which the argument rests; it's merely a lovely rhetorical ornament. (Let me add that construing the paragraph as a syllogism from premises to a conclusion is rather silly, even though Cambridge happens to be the birthplace of analytic philosophy. There's a thing called pragmatics, and the notion of argument being more than underlying logical form hasn't been controversial for 40 years. Rationality ain't just logics.)