I am not a lawyer, but... realistically sentiment has been moving away from the death penalty in Washington State since the 1990s such that even someone like Ridgeway was unlikely to be executed. I don't recall the last execution (I think I was a teen...) but even in those last few the appeals went on for years.
Last person executed was Cal Coburn Brown in 2010 for murdering Holly Washa in 1997. He and James Homer Elledge are the only two people executed by the state of Washington this century, Elledge was lethally injected in 2001, for murdering Eloise Jane Fitzner in 1998.
Gov. Inslee set a moratorium when he came to power in 2014, and the state supreme court found the punishment to be racist and hence unconstitutional in 2018. It has been illegal ever since. This law basically just removes an unconstitutional law from the legal code.
There is 0% chance that Gary Ridgway would ever have been executed by the state. There is also high chance that he would have given the names of his victims regardless of the plea bargain.
