I guess it depends on the point you want to make...
I would mostly agree, but my point point was more the other way around. Not that shearing is a thing you commonly want to do, but the fact the you should be aware that
c4d.Matrix will not enforce an orthogonal basis. Because if you thought it does, you could for example think that
my_frame = c4d.Matrix(v3=my_normal)
would be a sufficient way to construct an orthogonal frame where
my_normal is k and then carry out some transforms with it and wonder what the heck is going wrong.
This has, in fact, been a point I thought long and hard about...
What I meant with that passage was the story which has been attributed to many famous programmers who left a complicated piece of code only commented with "and here comes the tricky part". Usually told as a testament to both their technical genius and their communicative shortcomings. The often (at least silently) admired notion is that "everything is self explanatory for a smart person". Which of course is neither true nor very "cool". I feel you are drifting a bit into that direction.
About the linear algebra stuff. In my opinion there is no wrong or right there, you can do a good job with a very coarse and with a very fine model. Although I think often the geometrical meaning of linear algebra has been neglected in teachings about it. Especially Cinema's "matrices" (which in my book do not really qualify as matrices) can be very well explained as linear maps which will automatically will make all four principal transforms intuitively clear. Everything that is left then is to explain that matrices are just another way to write a linear map, i.e. a linear combination of vectors representing a coordinate system.