Face detection for different poses more robust than MTCNN?
If anyone is looking for something that is more robust than MTCNN, try this but you need GPU with Cuda I believe.
It says Tesla P40 on requirements but that is for training only. 
I could infer on new images with the provided parameters on a GTX 1080 with Cuda.
It's called DSFD from Tencent in China.  Their results on some well known benchmark datasets surpass MTCNN.
I can concur that it detected the above-mentioned side faces (not profile but lying sideways).
It is on Github:  DSFD Tencent
There is a demo.py where you can designate your own image as an arg on command line.  If you figure out how to use this with CPU only, please let me know.