read the book first and then comment on it ....
Hisham b hakam was the one most commonly associated with imami 12er theology , and the disgraceful practice of sabb-e-sahaba.Yes he does predate safavis and 12er shiaism evolved to its present form over centuries.What I mean was the state ideology of 12ers was finalized during this time as for the first time it got a clear majority in a muslim country. A lot of sources for 12ers are actually common with other muslims so that hardly counts as purely 12er works.
Our main sources are personalities like Shaykh Kulayni, Shaykh Mufid, Sharif Murtada, Shaykh Tusi, Ibn Idris Hilli, Muhaqqiq Hilli, `Allama Hilli, Shaheed al-Awwal, etc. and all their works.
The most important output of the Safavi era scholars was more in the encyclopedic re-compilations of these earlier works into the collections of Wasa'il and Bihar, etc. But that said, most of the sources they used predated that by centuries, and for the most important of them, like Kafi, Faqih, and so on, we still have the original books themselves separate from the the encyclopedic works.