The PS pump is driven off the vacuum pump. But unless the shafts broke a bad vacuum pump shouldn't affect his ps pump. And that's definitely not an intermittant.

ABS sensors can indeed give false readings and trick the system into an abs stop WITHOUT throwing codes r lights. It's actually pretty common around here, a little saltwater gets into the wiring and throws the resistance off or you get rust jacking that opens up the gap between the sensor and tone ring. You end up with a sensor that does pass the self tests for open or short and still generates readings, but they are off.

You need a scanner that can access the abs data to narrow down which sensors are acting up. But disabling the abs will narrow this down to an abs problem or not.

Knowing how abs works helps here too. The system can (and does) cut the pedal off from what ever wheels the computer thinks is sliding. If he has multiple sensors giving false readings he may very well have no brakes.