Mudge was a DARPA PM; that's a significant position in the sense that he led DARPA-funded research programs, but I don't think it's one that actually requires a clearance.
Source: currently do DARPA-funded research. No PM has ever mentioned having a clearance to me, and the work itself is entirely uncleared.
Source: currently do DARPA-funded research. No PM has ever mentioned having a clearance to me, and the work itself is entirely uncleared.