I have learned the hard way that to go for forgiveness rather than permission, especially when you know that permission is required, it is wrong. That rationale is deceptive, manipulative, and can have devastating consequences.
To move forward with an idea or a plan before getting the permission of others involved because you believe it is easier to get their forgiveness than to get their permission is wrong - plain and simple. It is wrong because it takes advantage of their good will. It is wrong because it violates the golden rule. And it is wrong because it is a calculatingly cheap view of forgiveness.
Keep living by that motto and one day you will discover there is no forgiveness.