How can they exit India if they never entered it? As long as they don't have a business entity there they can still keep running it, and it would be upto India

How can they exit India if they never entered it? As long as they don't have a business entity there they can still keep running it, and it would be upto India to create a national firewall if they so wish to, otherwise their citizens would be able to still access Signal without any issues.