That does sound like it could be exploited, but with only as much exploitability as some random app that requires your password (for analogy consider a Linux binary that refuses to run unless being run as root). Ultimately it's a matter of deciding whether you trust the developer of the app and whether you trust this app is really from that developer. The day Apple prevents users from giving root access to a third-app app is when the Mac fully becomes a walled garden, and you can expect pages of HN complaints.

Overall I think it's good paranoia to not grant root permissions to apps that do not clearly need them such as Slack.