Disclaimer: we still have pragmatic reason to follow the evidence suggested by our best scientific theories. I'm just poking fun at scientists in the spirit of Hume. There's no guarantee that the future will resemble the past, and even our best scientific theories are amenable to future evidence.
Why would any scientist worth their salt be mad about that? Science is constantly trying to find new things that may disprove old things, that's basically half of the point (the other half is the discoveries made along the way).
There are only very few things out there where scientists are sure they will never change and for all of those we know for a fact that they cannot change, like the fundamental axioms of math.
Fair enough, the meme wrongly implies that scientists don't know about this uncertainty or would be mad to learn about it. That said, my impression is that most scientists, even if they are aware, are not philosophically inclined enough spend time thinking about it. Which is why we still have a philosophy department.