I met him once in the late 1990s, when his travels took him to Zurich and he asked me whether I could book a talk for him at ETH Zurich, where I was a grad student.
I did not quite share his confidence in my abilities in that area, but to my relief, Jürg Gutknecht agreed to sponsor the talk, and I got to spend lunch with Brad Cox, Niklaus Wirth, and Jürg Gutknecht. Given their highly divergent aesthetics in language syntax, I expected some fireworks, but the conversation was quite pleasant, even when they were discussing Perl.
I was at the time the maintainer of the Mac port of Perl, and had taken some classes with Wirth, but the idea of discussing Perl with him struck me as akin to discussing masturbation with the Pope. However, Wirth conceded that in the area of text processing, general purpose languages tended to be somewhat clumsy, and there had always been a successful niche for languages like Snobol and now Perl.
Brad Cox was a splendid conversationalist in many other areas as well. His talk focused on Superdistribution as the next evolution of the Software IC concept, and he very skillfully pitched this to a Swiss audience that a banking nation should be a natural superpower to take the lead in a micropayment world. He was very good at painting visions like this, but I'm not sure how much of it ultimately came to pass:
a) I don't think we're any closer to plug and play "Software ICs" than we were in the mid-1980s when he introduced the term. In the Objective C ecosystem, the closest there was to that was maybe Interface Builder with its Outlets and Actions, but I think that part did NOT originate with Cox (I may be mistaken, though).
b) Likewise, I don't see any move to distributed micropayments. If anything, more and more of the software revenue seems to come from centrally billed cloud services, e.g. comparing the Microsoft Office revenue model 20 years ago and now.