The iPad in the setup described is just running a terminal with SSH. Emacs (and pretty much everything else described in the blog) is running on a remote server

The iPad in the setup described is just running a terminal with SSH. Emacs (and pretty much everything else described in the blog) is running on a remote server running Ubuntu (so I don't know why he even bothers to compile emacs from source). "Impressive" is not the word I'd use for running a terminal with SSH. Especially since the iPad is likely several times more powerful than the remote Ubuntu server that is actually running emacs.