That article says nothing about non-qualified withdrawals, only qualified distributions to pay expenses. I think the edited comment above points to the dispute on this topic because the IRS has not specified any limitations or guidance.
This is what was said a couple of years ago: Prior year scholarship withdrawal from 529 - #3 by BelknapPoint
The key issue is the interrelationship of kiddie tax and withdrawal date. Ideally you want to withdraw after your kid no longer has to pay tax on unearned income at kiddie tax rates. Assuming they get a job promptly then they are likely to be providing more than half their support in the year they graduate and their tax rate will be lower because they only have half a year’s earnings. So that is likely to be the sweet spot for withdrawal of the excess.