I’m picky about pronoun-antecedent agreement. For example, in one of the Twilight Zone openings, Rod Serling says: “A journey into a wondrous land whose boundaries are that of imagination.”Subject-verb agreement is my own particular albatross.
Really, a literate man like Mr. Serling should have known better. A pronoun must agree with its antecedent; therefore the correct phrase is “A journey into a wondrous land whose boundaries are those of imagination.”