I’m normally quite skeptical of these kinds of “Tesla More Dangerous Than Other Brands” headlines since they tend to be B.S. But this seems like a pretty legitimate accusation, and certainly a well researched write-up at the very least.
The author kind of plays this up a bit by insinuating that there are incidents we don't know of, and they probably aren't wrong that if there are five fatalities there are going to be many more near misses and non-fatal fender bender collisions.
But for the number of millions of miles on the road covered by all vehicles, extrapolating from five incidents is doing a lot of statistical heavy lifting.