Hello culbi,
For a better explanation of the reasons for not copying from Govmap, and what can be done to allow that, please read this entry in the Legal FAQ:

https://wiki.openstreetmap.org/wiki/Legal_FAQ#XYZ_Organisation_has_data_for_free_download_under_licence_N._Can_I_use_it_in_OSM?

Among other things, it clearly says:
> Do not rely on your own legal interpretation of the licence.

Thanks,
Zeev