It makes sense to me too.

Although behind a paywall a paper by Zappia et al. [1] states:

"Patients underwent an oral acute LD test with 250 mg of LD".

"In our sample, women were significantly lighter and had a significantly greater area under the curve than men."

That suggests that women get the benefit of more levodopa.

"Moreover, a greater percentage of women showed LD peak-dose dyskinesias compared with men."

That suggests that weight has some pharmacodynamic effect.

Also, I would suggest that as the disease progresses, and dopaminergic cells die off, reducing both the endogenous production and storage of dopamine, the more closely that the pharmacodynamics follow the pharmacokinetics.

Reference:

[1] "Body Weight Influences Pharmacokinetics of Levodopa in Parkinson's Disease
Zappia, Mario et al.
Clinical Neuropharmacology: March-April 2002
Body Weight Influences Pharmacokinetics of Levodopa in Parki... : Clinical Neuropharmacology

John