Seems to me like Donker was only attacking Kurtzman's talent as a writer, not the man himself. And while "worst" may be overstating things a bit, he's certainly down there. Just consider
the list of things he's written or co-written. It includes...
The Island (a criminal waste of good actors)
The Legend of Zorro (that's the sequel, not the good one)
Mission: Impossible III (that's the one Abrams directed)
Transformers
Transformers II: Revenge of the Fallen
Star Trek 2009
Star Trek Into Darkness
Cowboys and Aliens (I literally fell asleep during this one)
The Amazing Spider-Man II (
aka the one that everybody panned)
The Mummy (2017 version)
...and that's just a small sample. The man is
not a good writer. You'd be hard-pressed to find more formulaic, schlocky, half-assed screenplays on the track record of anyone in Hollywood (well, except perhaps Akiva Goldsman).