Because Google has infinite money, the execs just hire people so they can admire the zoo of smart people they've built. Why do they need Vint Cerf, Guido, and Rob Pike? Why are they on the MIDI board? Because there's no real reason not to.
Guido van Rossum (creator of Python) is a Distinguished Engineer at Microsoft. Before that, he worked at Dropbox.
I get the quarterly check-ins from the "alumni recruiting" team, and can assume Guido does too.