Netlify CEO here. Our support team has reached out to the user from the thread to let them know they're not getting charged for this. It's currently our policy to not shut down free sites during traffic spikes that doesn't match attack patterns, but instead forgiving any bills from legitimate mistakes after the fact. Apologies that this didn't come through in the initial support reply.
I’ve been a netlify user since 2017 and I just deleted all my sites. I can’t risk receiving a $100k bill for toy projects. Your “current policy” is not good enough.
I did the same last night from my phone. My personal site and a project docs site are just going to not be online for a couple days. Easy choice.