1) It looks to me that his qualification is at the level of offering beginner level courses. Nothing wrong with that. But it looks like he's advertising it as being otherwise.
2) Nothing wrong with copy pasting from other repositories either, as long as the code license copied from allows for such reuse, and you give the proper acknowledgements in return, instead of claiming that its yours. Its not uncommon to make use of 3rd party code for case studies, etc. But the main question here is, for such a course that he's offering, is such the expectation or not.
3) The bigger problem is largely to do with the larger than life hype, and his failure to cater for the expected number of participants (unable to scale accordingly). The dodgy manner of getting around Slack's 10k free message limit is another thing. Granted that Slack charges $6.67 per user, and for a 10 week course, it'll end up as being $20 per user, which is literally 10% of the course fees, this is something that he should have planned for in advance, instead of switching halfway. Either factor in the cost for Slack as part of his fees, or get everybody onto Discord at the start instead of doing it halfway.
4) Promises on job referrals is another huge mistake, and does sound rather suspicious to me too.
Make sense.