'And': Conjunction Reduction Redux By Barry Schein (linguist) has this passage:
How natural does whose sound?
Can you use who or whom instead?
If this were a personal pronoun, the nominative wouldn't be possible:
*He being a person contains the events of his career.
And either the accusative or possessive would be possible:
His being a person contains the events of his career.
Him being a person contains the events of his career.
Even though we need not a personal pronoun but a relative pronoun here, I wonder if the same case treatment is in order, i.e., if the nominative who is banned and only the genitive whose and the accusative whom are allowed.
In case the meaning of the sentence containing whose is difficult to grasp from the given quote, the metaphysics known to the speaker is this:
Just because you're involved in some isolated events where you act like one doesn't mean you're a superhero. You're a superhero only if you make a career out of being involved in all such events. And the same is the case with being a reporter.