Good point. Solid fuel rockets are quite different in construction than liquid fuel rockets. They are less worth reusing because what is left isn't as valuable as a liquid fuel rocket, but they are also easier to reuse post-dunking because they aren't as complex. It's still a wash for them.

Still, it says something that no actor has ever even bothered attempting to reuse a liquid fueled rocket that is landed in water. The only successful track record of reuse of liquid fuel rockets is the space shuttle, and those landed on a runway. And that isn't preserving the fuel tanks for reuse, mind you, just the engines.