You could set up auto-renewal. Good registrars also remind you when the domain is about to expire. In any case, using a custom domain is safer than relying on a single email provider.
Do registrars send you warnings when their algorithms detect that you've broken their terms of service? If not, it's equally as at risk as the article suggests Gmail is.
Example from 3 months ago: https://news.ycombinator.com/item?id=31573854
Another one: https://news.ycombinator.com/item?id=30506581