This model is, in fact, a human model of Parkinson's disease, if...

This model is, in fact, a human model of Parkinson's disease, if you think about how this was invented. Wikipedia tells:

"The neurotoxicity of MPTP was hinted at in 1976 after Barry Kidston, a 23-year-old chemistry graduate student in Maryland, US, synthesized MPPP (a synthetic opioid drug) with MPTP as a major impurity and self-injected the result. Within three days he began exhibiting symptoms of Parkinson's disease. The National Institute of Mental Health found traces of MPTP and other pethidine analogs in his lab. They tested the substances on rats, but due to rodents' tolerance for this type of neurotoxin, nothing was observed".

"In 1983, four people in Santa Clara County, California, US, were diagnosed with Parkinsonism after having used MPPP contaminated with MPTP, and as many as 120 were reported to have been diagnosed with Parkinson's symptoms.[12] The neurologist J. William Langston in collaboration with NIH tracked down MPTP as the cause, and its effects on primates were researched".

So MPTP-induced PD in primates is the same as the human PD, or as close to human PD as it is possible.

The big value of this primate study is based on this story, this model is a human PD model. Maybe, there have been more human cases of getting PD by MPTP than apes.