rsync has specific running modes for the super-user. It also pumps arbitrary data from the network onto your file-system. openrsync is about 10 000 lines of C code: do you trust me not to make mistakes?

No, but that's why almost nobody runs it outside of strict trust boundaries. This security section would make more sense if rsync was like curl, which routinely deals with hostile counterparties. If the other side of your rsync is hostile, you probably have bigger problems!

(I'm not an rpki person so I don't know if there's some part of that problem domain that changes this equation. I'm not dunking on the project, just saying this snagged me in the README).