(author here) Good point. TBH, I have no idea what "isomorphic" means in the mathematical sense.
I was inspired to use "isomorphic" from a 2011 article by Nodejitsu [1]. It seemed like a fine way to describe this approach. I would gladly use a better would if I were to find one.
[1] http://blog.nodejitsu.com/scaling-isomorphic-javascript-code