As Ray says, "mere aggregation" (i.e. not preloaded) is fine under GPL.
If the DONLP license allows commercial *distribution* freely, what's
the problem? We simply need to make sure to preserve the license on
the source file. If we want to be ultra-conservative, I suppose we
could have it print a load-time warning "Warning: The DONLP package is
not licensed for commercial use". We don't need to put it in a
separate directory, though I suppose another possibility is to put it
in share/noncommercialuseonly and not put that on the loadpath by
default.
-s