It's not really a straw man. Driving your application with tests at the unit level doesn't make a lot of sense, in the case of a web app at least. The BDD approach makes more sense to me. It's how I work and in my experience tends to inform design a lot better.
I think saying hexagonal design is bad therefore TDD is bad qualifies as a straw man.
Person 1 has position X.
Person 2 disregards certain key points of X and instead presents the superficially similar position Y. The position Y is a distorted version of X.
Here X = TDD is good.
Y = hexagonal design could be good for rails
Y =/= X
I'm no TDD zealot, I just think DHH's argument here is weak.
