He's not necessarily saying he know's a solution, just that such a problem should be considered. Satellites do collide - https://en.wikipedia.org/wiki/2009_satellite_collision

The idea of satellite collisions and space junk is an actual concern https://en.wikipedia.org/wiki/Kessler_syndrome .

Sure a few washing machines in space isn't a big concern. Now imagine a few collide, hundreds of bits and bolts flying around earth, at unknown trajetories, at thousands of miles per hour.

There are a variety of potential mitigations. Legal requirements that satellites deorbit or park in a safe orbit before going dark, technology like https://en.wikipedia.org/wiki/E.Deorbit to capture and deorbit large chunks, better tracking of orbital debris, etc.