I don't think there's anything new there conceptually; Stallman is quite aware that convenience is one way that proprietary software wins over users, because that was also true in the 1980s. What benefit would there be if RMS used an iPad? He's not a UI designer for any GNU software, so he doesn't really need to do it for field research. The main software he's involved with at all (mainly GNU Emacs these days, afaik) is not really targeted at the same demographic as the iPad anyway.