NASA's Voyager Found a 30k-50k Kelvin "Wall" at the Edge of Solar System

Can someone explain to me why this isn't melting Voyager?

There is no thermal mass. It's almost pure vacuum but the handful of particles that are out there are whizzing around at high energies that make them very hot.

Interesting to think that while it's not a concern to Voyager at its pokey 17km/second, a true interstellar ship traveling at some respectable fraction of C would compress the diffuse interstellar gasses enough to make them a potential hazard. You frequently see people saying stuff like "if we could accelerate to a high fraction of C you could get anywhere in the galaxy in a single lifetime", but it may not be so simple.