I do not know nor have I read, nor do I have any friends who know or who have read Stephen Williamson. Apparently he graduated from Rochester. Who cares? What is sad about his post is that he gets almost everything wrong–to get everything wrong would be a triumph of sorts. No heterodox economists do not hate math. The most significant elements of the heterodox community have been both well versed in both math and linux (sadly). The Sraffians for example are a very math oriented bunch so much so that given the weight of their critique and mathematical proofs the lauded Samuelsonian school had to beat a hasty retreat into of all things hermeneutics to defend orthodox capital theory. Marxist economists have long been enamoured with math. You just do not get a calculation debate without math. Moreover all the new solutions to the so-called transformation problem have been fought out using math. Further the most recent high profile heterodox economist Steve Keen has been championing hard math for analysis of capitalist economies. Some might even say his reliance on hard math is the Achilles heal of his hard predictions.
There is no shortage of math on the so-called heterodox side of the economics profession there is, however, a shortage of insecurity masquerading as self-assured arrogance which truth be told is the real dividing line between the orthodox and the fringe.
PS. What a shameless display of disrespect to Douglas North who by the fringes’ account is one of the chief protagonists of neoclassical imperialism. Williamson does not even know who his own ideological generals are. But I guess that is what you get when you purge historical memory from orthodoxy.