Systematic Discrimination is not an intent, it is a consequence.
As defined: “Systematic discrimination, also called institutionalized discrimination, refers to a method of discrimination which occurs regularly in the workplace as an inherent part of the company through interactions and processes creating a disadvantage for people with common set characteristics such as race, gender and disability over a long period of time. Systematic discrimination is not apparent at first sight but is actually systematic in its application of policies and practices.”
Similar evidence is presented commonly to explain why the executives are predominantly male, I'm not sure why the circumstances must be different here.
The average amount of time a person has been taught by a professor is a tiny tiny portion of the individual person education. It would be interesting to see a number for it, but I suspect its significant less than 0.1% of all the hours that the average person spend in the education system. Professors are under-represented in the education system.
This is not how "systemic discrimination" defined nowadays. You can't define systemic discrimination against men in one way (with intention), and define systemic discrimination against women in a different way (only look at specific outcomes).
If we define any difference in outcome as discrimination (which I don't find useful, but I'll accept it for the sake of argument), then I think we should make a clear distinction between discriminatory factors which the individual affected can control and change, and discriminatory factors which are outside of the control of the individual.
I don't question the particular claims in isolation, but they are obviously cherry-picked. If having more female middle-school teachers have a discriminatory effect towards males, then surly having more male university professors and are discriminatory towards women, right? Somehow women have still been able to overcome that, historically.