Why would you feel more insulted writing out a bit of pseudo code than answering a technical question?
If someone isn't comfortable with a complete stranger trying to validate whether they are the person described in the résumé, I suggest that they work hard on their networking so that they are always in a situation where the prospective employer is convinced in advance that they are a good hire.
He waved me off, that was good enough for him. The rest of the interview was then about cultural fit and ability to ship software on time without drama.
(And no, what I wrote is not in the same league as Clojure, much less the same ballpark. But it was good enough to demonstrate some basic understanding of Java and familiarity with undergraduate-level Computer Science.)