TOS and TAS told us that Kirk had no time for any meaningful relationships and that nothing ever seemed to come from them. TWOK taught us he not only fell hard for someone but had a son with them.
Does that make Kirk inconsistently written? No. It just means he never mentioned Carol or David in TOS or TAS.
Does that make Kirk inconsistently written? No. It just means he never mentioned Carol or David in TOS or TAS.