I think the concept of an accessible font is signaling. I don't think that Times New Roman is actually less legible than Calibri, and have never seen research claiming to find that Times New Roman in particular or serifs in general pose accessibility problems.
I easily found some research by searching Google scholar:
https://www.scitepress.org/Papers/2021/109668/109668.pdf
It's not a big difference, but apparently TNR was the worst of the fonts tested for OCR.
But anyway, there was no "signaling" about the change to Calibri. No-one ever tried to make a political issue out of it the way Rubio is now.
"Decisions I know nothing about are signaling" is a phenomenally uncurious approach to life.