Even if it's just a test, it seems a reasonable scenario that just the test will cause permanent damage. I understand trying to promote better discussion, but this system is downright unwelcoming to any newcomers. When I registered to comment I thought the downvote restrictions were odd and I was willing to try it out, but if this was in place I'd have closed the tab and never come back. Maybe subject-matter experts wouldn't be so put off, but novices and students like myself would feel shunned. That's not saying I'm the most valuable poster, but I am far from a troll and I contribute real opinions and questions. I think lesser experienced posters like myself are important.
I also fear that this may fail silently with an echo chamber as a result. I think this is a real concern here. Unless there is a great amount of monitoring on those posts that don't make it through, none of the automatic posters may even miss the ones who never get a voice. That doesn't make it a positive change though.
I hope you reconsider this change,
A concerned member of this community