Personally, I prefer to invent a subject for such a thought experiment and then use the appropriate pronoun for the person's gender - which is what you did here with Theo.

The problem with inventing a subject is that people may notice a (unintentional or even nonexistent) trend to always cast one gender as the brave, smart, rational protagonist and the other gender as the cowardly, stupid, silly antagonist.

Personally, I don't care what technique is used (fictional subject, always "he", always "she", "he or she", "they", invented pronouns, etc.)