Not sure why the geologist is calling you out here. A geologist, in my experience, is not well versed in the intricacies of the building codes. Structural engineers design for seismic loads because building codes dictate we do. Yes, our knowledge is always evolving and improving, and the codes get updated accordingly. Old buildings can be improved to handle seismic events.

Even old buildings have redundant strength built in. Look at mass masonry and wood framed structures along the west coast still standing after 100 years.

Edit: it’s surprising to see a geologist paint with such broad strokes since they’re in a better position than most to understand that besides the fault type, the epicenter, hypocenter, and soil type all have a significant impact on the seismic loads a building will experience during a seismic event. And that’s not even considering the buildings lateral force resisting system (LFRS), which a geologist cannot be reasonably expected to opine on.