The reason an advanced Neuralink could be invaluable on Mars is because all the complex machinery required for diagnosis of brain-related ailments will be prohibitively difficult to set up on a Mars colony for a good while. The brain is the least understood ogran in our body - Elon is trying to accelerate development and generate awareness in the field by giving it an honest go with his own company. A BMI like Neuralink would also be a multiplier of human effort when there is a limit to how many colonists we can ferry per unit time.

Neuralink aside, you seem to not have mentioned the other companies - I wonder what you think of my theory regarding them?