Carol is a character in a comic strip. Her character would never have used the word "whom" in that sentence.
Perhaps there could be a "grammar police" character working in the same office as Dilbert. Having someone spend their time correcting the speech of others may be a basis for a few laughs, but only if he/she meets with a gruesome demise.
Nobody cares anymore whether it's "who" or "whom." Nobody uses "whom" anymore - whether it's called for or not. "Whom" has gone the way of the hyphenated "good-bye" and people wishing each other "glad tidings."