AFAIK the point of the LGPL is that the LGPL license parts must be replaceable with a user-modified version. The easiest way to achieve that is through dynamic linking, but it's not the only way. They could release object files of their library and the LGPL licensed parts, document how to replace the object files of the LGPL licensed parts if you wish to do so, and how to link the whole thing into a dynamic library.