I have mixed feelings about this. I do like the idea of transparency on companies who do not pay. But I worry that it validates the overall concept of credit scores, which can be damaging to individuals. Maybe the same features with different terminology could resolve that?
The problem clients I've dealt with are not the one who do not pay, but the ones who just push the limits. I had a contract with one company who insisted on net 30 payments terms when we signed the contract, but would not even start their payments process until day 31, so in reality they were late every single month. I did not renew that contract, and will not work with them again, but I could have avoided them entirely if I knew how they operated. If this app removes listings when they pay, that hides such practices, doesn't it?
I also worry if one company controls this scoring. It seems ripe for misaligned incentives if the company that tracks and reports scores also monetizes the process. I didn't see any details when skimming the web site to see if this is truly a problem or not, but clarity on the integrity of the process would be important if you carry this forward.
One final note - I tried a couple searches and it just said the company was not found. That removes a ton of confidence that you have enough data to try this. Even if you have no records on a company, make the effort to pull lists of companies in, so you can confirm that you are aware of what companies exist, but have no records on file related to them.