Well, that might be the most generic description of what an antibody does, but this article is clearly drawing a distinction between "antibodies" and this "manufactured molecule" with statements like this:

"Because of its engineering, the mini-binder can also withstand wide variations in temperature, making it extremely convenient, unlike antibodies that must be kept cold to preserve longevity."

So maybe we need to rethink the definition of "antibody" as well as "vaccine." In both cases, you could define the word by its effect, by its mechanism, or by its structure. It sounds like these molecules are simpler and sturdier than actual antibodies so the structure is clearly different. Both of them bind to the antigen. What happens after they do that may be different?