They ruled that it's like a journal, or a tool like a search engine. This seems fair.
At what point does it become a 5th amendment issue? Maybe when we get AI in our corneas a la Black Mirror's The Entire History of You?
It's more likely to be ruled in your favor if you started the research after being arraigned, and choosing to represent yourself.
But if you were just googling "murder defense theory" and are accused of murder, they'll be able to use that against you.