It would have been very interesting if they were the same person, but I'm pretty sure they're not. The dude from Fugazi is Ian Mackaye, he was also in Minor Threat, Embrace and some other more minor projects - he's one of the most famous personalities of the DC hardcore scene, but he does not espouse anarchist beliefs. The anarchist writer is Iain Mckay, the editor of 'An Anarchist FAQ'; note the differences in spelling, if that's the guy who writes for those magazines you mentioned (I assume it is given that he's the only Iain Mckay of any spelling that Google associates with anarchism).