I'm not sure that I fully agree with your analysis, even though I think you've explained it very well.
Buying 500+ missiles for four platforms assumes that the PLAN had, in 1995, the resources to dock and reload their Sovs numerus times in the event of a hot war with the US Navy. This is quite difficult to digest, given that the US would have had total electronic, aerial, and naval superiority under the circumstances of that time. Drawing from a 1996 incident in which a single US Navy Prowler shut down the entire Nanjing military district's systems, it was very doutbful that the Sovremennys would have lasted long enough for weapons reloads of that frequency. It is odd why the PLAN did not choose to go for more Sovs and less missiles.
I think you have it the other way round.
China didn't so much buy the Moskit/Sunburn for their Sovs, rather, they bought the Sov to get access to the Moskits.
In that respect, I seriously doubt they would have relied on the Sovs as the only, or maybe even primary delivery platform for those missiles.
Given how much Russian tech China was buying back then, and the fact that the 052B DDG is in effect a Chinese indigenous version of the Sov (sans the Moskits interesting enough), it would not surprise me at all if China developed coastal AShM batteries capable of using Moskits.
In addition, it would not be outside the realm of possibility that their Su30Mkks and MK2s might be able to launch Moskits, especially if reports from the late 90s and early 2000s about China either cracking or having acquired the Su27 and MKK radar system source codes prove accurate, as that means even if they Russians didn't integrate the missiles for China, the Chinese could have done it themselves.
But we are getting into speculation territory with that, so I will leave it there.