Why are you so sure it needs any disclaimer?
Call recording (the action itself) is regulated in some regions, hence the disclaimer. Duress pin (the action) is not illegal in jurisdictions I know of, only the consequences are. It is similar to camera sounds being switched off, where the action itself is not illegal, and hence needs no disclaimer (not even in Japan).
To yield before establishment of law is just giving up rights, and that does not seem to be the philosophy of the project.
DeletedUser1026 to be used stealthy
There is nothing to be gained here. A common misconception is that people only need to fool an individual agent or police. But the agents or police do not know anything about how to examine devices, they use dedicated tools for it (hence all the reports about them taking the phone somewhere else while they detain you), and these third party apps can easily diagnose if you use GrapheneOS and if you had an extra profile that you wiped. There is just too much forensic evidence to actually do this cleanly.
Even systems like Tails that live entirely in RAM often are caught in simple forensics like viewing hardware logs or swap on hard disk. It is not trivial, nor advised to depend on some stealth feature in some obscure software for security, since forensic vendors' jobs involve studying and documenting these systems as much as possible.
Here is another relevant discussion on a similar topic: https://news.ycombinator.com/item?id=48974862#48995485
Please note that I do not speak for the GOS project (I wish I was that badass). Also I love how people keep adding this line, because it is funny to see this as a frequent forum user, but I absolutely understand the need to clear this up for new users.