The rep is totally wrong to say that you need a sacrificial anode in a powered anode system for the latter to work. I’ve been selling powered anodes as a replacement for factory ones in softened systems for odor for three years and nobody has had their water heater rust out and nearly everybody solved their odor problem.
Now I’ve decided they are valuable in softened systems without odor because of how fast softening consumes anodes.
The trouble with reps is that you can never know where they got their training. We got ours in the field, so we’ve actually seen cases that reps and even factory scientists merely speculate about, like passivation. On that one, my experience has proven their theories wrong.
When I was doing inspections, I occasionally ran across Fourmost commercial heaters. Rusted out. They had powered anodes top and bottom AND four magnesium ones. I’ve always wondered about that.