To me this is an undecidable, but it’s not of the “What in the world?” type, but just which of a few basic alternatives. It could be the speaker is right, and the particular paintings in this gallery are setting the kid off. Or the kid is just tired and cranky, and being still walking around anywhere in the museum would set off the tantrum. In which case the speaker is probably just dense and mistaken (and we’re amused at him); or he is attempting a joke of his own.
Comics I Don't Understand 
Yes, I think the guy is just making a joke. If the toddler had been having a standard tantrum in a massive supermarket aisle he might observe “Wow, that kid is really upset at the way monopolistic corporations exploit their low paid workers and squeeze small-scale farmers“.
I enjoy seeing how Bliss has created in miniature format an O’Keeffe flower painting. Is anyone here familiar enough with her work to identify this as based on a particular identifiable model? Or would it be more a matter of capturing a style?
Perhaps it /is/ meant to be somewhat “about her”. The suggestion would be that the child could become distressed by O’Keeffe’s sexualized nature imagery, even while not knowing that’s what’s doing it.
I think it’s just sarcasm. I can imagine this being amusing in a scene from a comedy. Especially if it was said in Steve Martin’s voice.
Gee – I just thought it was a funny cartoon. Maybe some of us are overthinking a bit ?
Ah, Mary McNeil, you touching naïf! When we find it here, we’re obliged to fuss over why it is funny or how it is funny or whether it is truly funny ..
Is it possible to overthink a comic in this forum? It’s kind of what we do.
beckoningchasm: Yes, it IS a scene in a comedy! With Steve Martin. “He hates these cans!
Overthinkers Pseudonymous
The drawing is pretty close to “Jimson Weed” (1932), especially the lower-right quarter.
https://www.georgiaokeeffe.net/jimson-weed-white-flower.jsp