What I meant was that the LangSec people reject the robustness
principle as it is commonly understood (i.e., make a "reasonable"
guess when receiving garbage), not necessarily that their view is
incompatible with Postel's original vision. This interpretation of the
principle is pretty widespread; take a look at the Nginx mailing list
if you have any doubt. I attribute this to the same phenomenon that
inverted the meaning of REST.
-Ben