Here "top-level" refers to repl and program body top-levels, but not library bodies.
One interpretation is that these behave like library declarations, and can expand into import forms. In this case, for a purely static implementation of R7RS libraries, they must first be statically scanned from all top-level forms. They cannot be used outside the top-level, and are not even available as bindings otherwise. This is the declaration proposal.
Another interpretation is that they are just normal macros with the obvious definitions (cond-expand in terms of the output of the features procedure), are available in the (scheme base) library, and consequently can't be used to expand into import since imports have already been resolved. This is the syntax proposal.
Alternately, we could provide both. If you think this is all too confusing you could also vote remove, to drop these extensions.
Related is the matter of whether multiple import forms are allowed in programs or only one may allowed as in R6RS. With either syntax or remove it could make sense to add this restriction, so the /single-import variant is provided. Note the repl allows allows multiple import forms.