Let's travel back in time to a few days ago, before these allegations emerged. Mike Lynch seemed like a guy who'd founded a high tech software company, let it grow, and sold it for billions of dollars. He's got an engineering PhD from a top university.
Over the last 10 years technology like the web, podcasts, home broadband, iPlayer etc have had a lot of impact on the BBC. It makes sense to have someone on the board who has an engineering background and experience managing complex technology projects.