We need a license model such that AI is only allowed to be trained on content were the license explicitly permits it and that no mention is equal to it being disallowed.

That is the default model behind copyright, which basically says that the only things people can use your copyrighted work for without a license are those which are determined to be “fair use”.

I don’t see any way in which today’s AI ought to be considered fair use of other people’s writings, artwork, etc.