Thanks for letting me know about this. You should still be able to run LiSSA by overriding the block, but your Mac is correct in saying that we aren't a registered developer. Unfortunately there is a significant extra cost to becoming a registered Apple developer so for the moment we are waiting to see how popular LiSSA is before deciding whether or not to register. I hope you understand.
Thanks for the feedback. We hope you find LiSSA useful.