It's not even necessarily problematic that women aren't involved in STEM. It might be an issue if they are being actively discouraged, and thats a legitimate debate but that's not been proven just asserted. There have been.... other assertions, but they must not be discussed as any intellectual should know. We do not talk about the uncomfortable, even if we are able to rule it out.
All that is aside from this though, which is in fact, much ado about a shirt.
I recall your nonsense from other posts. This would be a good try if you were relatively anonymous and the whole vague dismissal coupled with ad hominem attempt was a new tactic.
Trying to shoehorn this shirt into STEM participation is academically bankrupt. There are deeper issues at hand. Gender differences in brain development makes mathematics and logic more easily understood to the average male compared to the average female, while women are on average better at communicating and empathy.
Coupled with the shitstorm that is high school where social groups are heavily aligned by gender. Part of the discouragement is from female peers sticking together socially which means that particularly the mathematically rigorous STEM subjects are more likely to be avoided because some of the group don't want to continue in the subject.
A lot of the female targeted science outreach stuff focuses on this without saying it outright. When you get past high school there is going to be a peer group at university and you will fit in. In general this is working as many have pointed out that STEM is getting more equal than it has been.
Of course not all subjects have been effected equally with many more women in Biology and Chemistry fields, Mathematics and Physics is doing OK but Computer Science and Engineering are lagging behind. (This is just from numbers I have seen at my institution)