What I see in the photos are crocs surrounding an already dead, mud covered hippo that appear close to being corralled by a line of live hippos who do not seem afraid of the crocs at all. Definite wariness there.
I always thought Hippos had the upper hand because they were so large. I might disagree with the author’s assessment of the situation.
Hippos, like elephants, appear to mourn when one of them dies. They’ll often linger for days around the carcass, loathe to leave. Crocs are the garbagemen of the river system..