Surely coercion is ok when the parent is right and the child is wrong?

Being fallible implies that we can be mistaken including when we feel certain that we are right. And because we are fallible, there is no reliable way to know who is right and who is wrong. Disagreements can either be resolved through reason, or they can be dealt with coercively. So no, feeling that we are right does not justify coercion.

Identifying coercion is itself a creative task

Overt coercion is less likely to corrupt children’s interpretation of what is happening to them. But given that part of our self respect as parents taking our children seriously comes from being non-coercive, it might well be that the coercion we inadvertently engage in is interpretation-corrupting double binds. So we need to be particularly aware of the subtle mind-messing forms of coercion.

A lack of forcefulness is good not bad

A lack of forcefulness is not a negative characteristic unless you find yourself sacrificing your own desires. You respect your children and take their desires seriously. You need to be sure to respect yourself and your own desires as well.