As a business model it is quite interesting. I don't think the spin of being an alternative to university is fitting though. It's either a service where you take classes for fun. I can see that working if marketed to the right people. Or it is a service where you take classes to improve your skills. I can see that working too. Lots of people in tech especially want to make the switch from DevOps to SWE to Data Science to Quant ...etc

As for the whole "professor" thing. A professor does research and a big part of the appeal of taking their (graduate) classes is to be able to have a glimpse of the research they do and maybe get an opportunity to work with them. This seems to be missing here. I am not saying this to downplay the idea. I actually like the concept.