More detailed studies would be required to actually confirm the link between C-sections and evolution, as all we have now is a hypothesis based on the birth data.
Agreed, more studies required part. Cesareans may simply be becoming more common with “too large” defined as cesarean seems like a better idea. It's reasonable to pose the question based simply on an understanding of evolution. Like it's reasonable to conjecture that length of human pregnancy is a compromise between further development in utero, and chance of mother and baby surviving the delivery.
"There is nothing new under the sun, but there are lots of old things we don't know yet." -Ambrose Bierce