"Any serious attempt at terraforming Mars,
must include the introduction of a moon that's large enough to turn the inert core to a robust dynamo. . . . . . . "
My emphasis.
I cannot understand this obsession with terraforming. How long into the future to catch the odd moon and stick it around Mars? I do not mean this disparagingly, but to contrast with the possible motivation to leave Earth in large numbers, and the possibility of slowly increasing colonisation of Mars. Apart from asteroids, any reason to leave Earth might similarly threaten Mars; e.g., expansion of the Sun.
Slow colonisation of Mars might be achieved without moving moons.
Cat