What to do about an unprofessional instructor?
Well, my answer is twofold:

First, the teaching method ssems like a misunderstood version of inverted classroom teaching - maybe an explanation how the teacher could support the students better might help. But it would be best if this comes from the course members or some students organization and not from an "outsider" not involved in the class. 

Second, the "bad coding style" - it's hard to tell what is good or bad without context. Some problems are obvious (e.g. "unpythonic" using of space characters, typos) and you could point to the official coding guidelines which are worth reading for any programmer anyway. Maybe you can suggest those as course material. 

All other "probelms" you identified could be part of the teaching concept and there are rationales for each:


I would not introduce string.digits (and any other library method) to beginners unless they see a need for it. The task given could be a step towards generating such a need. 
The mix of ' and " could have educational purposes as well (even though I would have used an example like my_string = "let's say 'Hello'").
List comprehension is hard to understand for beginners. It is a powerful concept for intermediate or advanced programmers, but usually beginners are having trouble understanding the nature of a loop. 


Maybe you can offer to support the course as tutor / student teaching assistant or else, with this you could influence the course content and improve the overall situation.