In general, creating a burner email account and using it to leak stuff to me is actually very safe.

My server is self-hosted, is full disk encrypted, uses cross-jurisdictional shenanigans to make subpoenas difficult, and if you leak anything to me that is relevant to my interests I will delete the logs of where it came from and have the technical skills required to sanitize documents.

This is not just about lawyers, but anyone with access to documentation around decision-making regarding human rights at organizations, or who has damaging information on anti-trans extremists can do the world a favor.

Do the right thing.