I guess depending on your political agenda they were either trying to be inclusive and promoting gender diversity in STEM, or they were being subtly misogynistic by implying that women aren't as careful as men.
Or maybe it was just arbitrary and maybe we don't have to read anything into it? But what do I know.
Nah, I actually believe it's the first one. That's why it's so hilarious. The irony is what it insinuates about what happens to women in STEM.
Women outnumbered men in my chemistry course.
And they both use substances that would destroy your eyes.
On a serious note: What are you on about?
Yes, I agree. That's why making it a girl is so hilarious. As to why you're so offended that I find it hilarious, I honestly don't know what to tell you. It's funny for the same reason I'll refer to a hypothetical serial killer as "him" and follow by saying "or her, of course" to females as if I'm pandering. The joke is that they weren't offended to be excluded from being serial killers.
It's part joke and part telling people "hey, this stuff is really dangerous, take it seriously or you'll lose an eye, or both". I don't think I've seen a single lab with high-powered lasers that didn't have a variant of this sign.
A similar popular sign for chemical labs is "Carol Never Wore Her Safety Goggles. Now She Doesn't Need Them", depicting a blind woman with sunglasses and a white cane. (https://knowyourmeme.com/memes/carols-safety-goggles)