V/s selected, with situational awareness, would prevent this. Energy management and good neighbor policy.
Had a corporate jet descend from FL410 to FL340 towards us. We were at FL330. TCAS "descend". Notified ATC. ATC apologized - "we didn't expect him to descend 7,000' in one minute. Jet 123 please call this number..." Violation of RVSM standards.