RMS is basically offline most of the time and gets a crap ton of email -- from the general public, from the GNU project and from his colleages at the FSF.

He spends most of his waking time running GNU, the FSF and answering people who have questions about free software. When he's not doing that, he's giving talks or getting a little bit of sleep. He spends a lot of time on a plane.

Other than working through mail in batches, including offline copies of webpages, would you suggest he get this same amount of work done in the time he has?

I am making the point that just because RMS does not use modern browsers does not mean that is is unfamiliar with them.