I think it is healthy. There is basically nothing to be worried about that dealt killed by water or heat. A hot pan is twice the temperature of a medical autoclave.
Soap is more of a cleaning aid for removing flavor than a safety control.
A little mentioned downside to cast iron is that it's porous enough that it will absolutely absorb certain things like turmeric that will only come out once you cook something else in it, no amount of washing or soap seems to make a difference past a certain point. Kind of a non issue to me, just a quirk of the tool.
Soap is more of a cleaning aid for removing flavor than a safety control.