Unclear antecedents happen if you're using he or she. Avoiding the use of they doesn't help, and using 'he' as a gender neutral singular most certainly doesn't.
a pronoun-antecedent error is more likely to occur with a third-person, indefinite pronoun, than it is with a first-person singular pronoun
I think there's a miscommunication here. migo was talking about use of gender-neutral "he", not the first-person singular "I". As an example of what migo is talking about,
"Bill waved at someone on the opposite platform, but after the train passed, they were gone."
versus the same using gender-neutral "he".
"Bill waved at someone on the opposite platform, but after the train passed, he was gone."
In the latter, it's unclear who was gone - Bill or the gender-unspecified someone. This is a case where having a gender-neutral that is different than the masculine helps. On the other hand, singular "they" also has its unclear cases, like:
"Someone waved at a group on the opposite platform, but after the train passed, they were gone."
I'm not sure how to estimate how common the different cases are. I'm also not sure if most specific is always the best way to determine the pronouns to use.
but I agree that simply using "he" everywhere may not be a good option either if it creates confusion. This is why I avoid the use of pronouns when I can.
That's reasonable, but also, most cases of unclear usage are obvious and can be avoided, while still using pronouns to simplify.