He does not want your code anyway, sqlite is public domain. this has several implications. One of which is the author wants nothing from you. Note that public domain is fundamentally different than the usual method of releasing code, which is to issue a license to distribute a copyright protected work. Putting a thing into the public domain is to renounce any ownership over the thing.

I think that the proper spirit of the thing is that if you have patches to sqlite is to just maintain them yourself. if you are especially benevolent you will put the patches in the public domain as well. and if they are any good perhaps the original author will want them.

In fact the public domain is so weird, some countries have no legal understanding of it. originally the concept was just the stance of the US federal government that because the works of the government were for the people, these works were not protected by copyright, and could be thought of as collectively owned by the people, or in the public domain. Some countries don't recognize this. everything has to be owned by someone. and sqlite was legally unable to be distributed in these countries, it would default to copyright with no license.