Obviously trying to infer if there is an admissions advantage for individual applicants is tricky business.
But if I understand their statistics correctly, only 3519/17068 in-state applicants applied RD. For sure that is going to mean only a small fraction of in-state admits applied RD, and then even more so as a mathematical consequence of the RD admit rate being lower.
But again, as to why the RD admit rate is lower, that is a complex question.