Monitoring the Removal of Office 365 Groups (and Teams)

That's right, and I have updated the article.

However, the downsides of using activity alerts (or alert policies) is that you depend on the ingestion feed into the audit log, and that happens at unpredictable periods. You also depend on someone going to check out the deleted group when the notification arrives. Sometimes admins lose track of events that arrive in email notifications because there can be so many of them in a busy tenant. My preference is therefore to have a more focused and proactive stance to the issue... but if you don't want to write PowerShell (or use code that someone else has written), then you can certainly use activity alerts.  https://www.petri.com/office-365-alert-policies-automate-audit-monitoring