It's an interesting argument in theory, but in practice the government in my country of origin actively searches through people's phones to find evidence of wrongthink (e.g. donations or incriminating social media activity), for which they sentence people to incredibly long prison terms.

The latest example: https://en.zona.media/article/2025/08/27/irin

That said, no matter how secure GrapheneOS may be, for this particular threat a permanently clean phone is a necessity.