Given the size of the ESM mast on the 54B, the assumption was always that it was going to favor quieter launches as it clearly was designed with a focus on lower emissions, and since newer YJ-83s seem to have imaging infrared sensors, they would perform better in cluttered or littoral environments. The choice of missile is likely more determined by intended mission than a singular focus on avoiding interception. Subsonic missiles are never really going to be a good option against ships bristling with sensors in multiple bands and wavelengths, as well as terminal defenses. The bar to target them and hit them is simply too low, its essentially a solved issue. Supersonic missiles have significantly less forgiving kinematics, and are theoretically far better at evading layered defenses with air cover, the kind that a CBG would provide. Their speed reduces the defended footprint of a single system because defensive missiles at the edges of their range don't have the energy to reliably strike fast targets, whereas if the subsonic missile is detected early, by say an E-2, its got a lot more effectively defended airspace to cover.