In fact, I find this rather nice summary towards the end of the article:
"In particular, EHT’s simulations show all of the effects mentioned above; there’s none of this of which they are unaware. [...] Thus it’s not enough to argue the photo itself is ambiguous; one has to argue that EHT’s more subtle analysis methods are flawed. No one has argued that yet, as far as I am aware."
To me this reads very much like "I probably shouldn't have used 'controversy' in the title".
Eyeballing it you can't judge much at all, maybe the central hole is really smaller, maybe the ring is a little thinner, maybe not. It is a Rorschach test as much as anything else.
If that's just the way it is I'll accept it, but I haven't heard or seen a good explanation yet.
Their advisor, who provided them the relativistic equations they use for the computer graphics simulation is Kip Thorne: https://en.wikipedia.org/wiki/Kip_Thorne