I see. This seems reasonable, but I think it can be checked by whoever the submitter is and one doesn't need to get some agreement from the package authors (although it's obvious good for them to know the rules). If down the road a package breaks the rules it will simply be removed (someone is bound to notice this). Anyways, given how few Emacs packages today require some non-free software to work, I'm not particularly worried about this.
> If something is a well structured package and it's licensed under GPL
> that's all we need IMO. After all NonGNU ELPA doesn't require
> maintainers to do anything special on their end, which means there's
> no real reason to contact them about it.
Reviewing the rules[0], the point is not to check up with every
contributor like with ELPA, but to ensure that the functionality must by
default not depend on non-free software, use SaaSS or install software
that is not part of {GNU,NonGNU} ELPA.
--
Philip Kaludercic