Your 14 day return policy is for the reasons, does not fit or change of mind reasons.
eBay's 30 day MBG policy covers buyers when they receive an item not as described, broken, faulty etc. so yes, they do have 30 days from the item's last estimated date for delivery to claim for a refund for those reasons.
The MBG policy's 30 days would not cover change of mind / does not fit reasons.
@amuzenterprises