While it's possible to unit test GUI interactions, I will say that in my experience it's very difficult to do well, and very easy to do poorly.
If we look back to the very beginning of this discussion topic, it was basically a bunch of people on the forums asking to be added to the list of GitHub reviewers. Might we take the same approach to people who are allowed to commit to the Greenhouse? Have devs ask to be permitted to commit to the Greenhouse. Whoever maintains that list of people can set whatever standards they see as necessary (X number of forums posts, Y days since joining, Z accepted PRs, etc.), and can adapt as needed if there are problems. It adds a small amount of work, but might be enough to keep the greenhouse safe enough for the brave alpha tester types out there. (chrisb is right, I regularly compile and run code that I have never even looked at... in fact, I often do the code-review part of PR testing while the compile is running!)