Read the league rules. It is clearly stated that sometimes 9th or lower-placed teams could also be promoted to fulfil the needs of draws into a new season.
Also read the association rules. League position in top3 gets a x3 multiplier; top4-8 gets a x2. Anything else gets a x1. Never was the promotion factor being included in the multiplier allocation as well (It is your own presumption to link these 2 together, but not suggested in any criteria as stated).
Read again if you are still confused.