How can I run an unsigned script in Automator
The exiftool installs into /usr/bin. Under SIP this is not permitted.  I assume the developer will change this at some stage.

If you install in /usr/local/bin it should work, and you won't have to override anything.

EDIT
I believe the latest has been changed to install in /usr/local/bin I have never bothered to install it myself, I just run from a local directory.