Several items to point out. If the business flags a negative review that mentions the event, Google will remove it. I doubt the business would flag a positive review referencing the incident. User can and should flag those reviews to help balance the ecosystem.
Google has been known to monitor business that make the news. The normally prevent new reviews from being posted and remove any new reviews from being left. I am curious who the business is as I would like to take a look.
There are multiple issues happening. The Google My Business (GMB) website is not impacting reviews nor are they being removed when creating them. You can use the free website as another property to rank in Google for your company name without it being linked from your GMB dashboard.
As far as...