Bob Fry writes:

Yeah...but they should also train the controllers on how to ditch
their various accents themselves, slow down a bit, and deal with ESL
pilots. The burden can't be 100% on the pilots to understand
controllers.

False. This controller spoke very clearly; his accent was completely
unimportant. The pilot's English was horrible, and completely unacceptable.
All of the fault rests with the pilot.

You cannot "deal with" pilots who cannot speak English. There is nothing you
can do to make a person understand your language if he cannot understand it.
This pilot's English was so poor that no action the controller might take, and
no English accent he might have used, would have sufficed to allow
communication. The pilot was simply incompetent in English.