Check the missile with the canted nose. Its either meant to represent a modified YJ-83B with the infrared imaging seeker, given taht there is no other missile in Chinese service that's like this, or something similar to it. Its also poking out of the first section, which is the 7 meter. The second and third sections are 9 meters, where you can see the two stage missile.
View attachment 88106
I should add that these canted nose missile, supposedly a digital IIR seeker, isn't just for antiship but for precision attack on land targets which is right now, a large gap in the PLAN's capabilities, although I don't know or not, if this capability was deliberately left out for the land based rocket and cruise missile forces. The use of precision land attack missiles by the PLAN would mark a major change in their doctrine, and in my view, a much needed one.
They can begin to use such either with a brand new airframe or an existing airframe like the YJ-83B, which would undoubtedly be cheaper and heavily shortcut the development process. I would think that using a VLS YJ-83B, even with an expanded booster, might still fit within the 7 meter maximum requirement of the smaller U-VLS canister, which allows for more available cells to be used.
Going back to antiship missiles, I do not think it is absolutely necessary for them to be VLS'ed unless you absolutely need and want to use the YJ-18. Deck mounted slanted canisters have their advantages. You can save the space below deck for something else, and you can change the slanted canisters and stands easily for something else. For certain ships, they can be added, like having 8 launchers in peacetime, but there is enough deck space to add 8 more during wartime. The canisters can be made shorter, and the missiles shorter and lighter. If a slanted canister is used on deck, you would have to use the YJ-83 or YJ-12 missile. A stealthy LRASM equivalent can use both slant and vertical launch. The advantage of a slant launch is that your booster does not need to be as big, so there is savings in weight and size. While the advantages are minor, ship space and weight is like wringing water out of a moist towel, you want every little bit of it from the little you are given. I also think the YJ-83 can be potentially VLS'ed if so desired, so the real question of choosing slant vs. VLS is going to reflect on another issue, the slant mounted YJ-12 vs. the VLS'ed YJ-18. Which is the better missile and which would you prefer ultimately?
The advantage of using IIR antiship missiles is to deal with stealthy combatant ships in the littoral zones where there is plenty of clutter from rocks, islands, and things beneath waves. Antiship missiles with radar guidance, which includes typically like your YJ-12, YJ-18 and earlier YJ-83 would have problems on such. Hence the use of the IIR seeker YJ-83B would fill this gap, and is an important capability among smaller and intermediate ship combatants, like 022, 056A and so on. That also makes sense for it to be added on the 054B's tool kit, whether it is the YJ-83B, or some equivalent successor.