Enough to make a hypothesis Im 90% sure is right.

So the starship is made of steel that has a really high melting point, so the starship doesn’t really need the heat shield while reaching space, the heat shield is meant to protect the starship from the temperatures that are achieved during re-entry.

Since the starship manoeuvers itself in a way that only one side faces the atmosphere during re-entry, only one side needs to be covered with the heat shield.