Main problem in Harry potter fanfiction is that Rowling sacrifices world for drama. When you first read books they are great. However when you try to write fanfiction you start to judge by his actions instead first impression. When Dumbledore faces decision between what is right and what is convient for plot he mostly chooses later.
When you take ideas what could Dumbledore do to logical conclusion he looks like worse death eater than Lucius Malfoy. Take DA for example. If Dumbledore created similar club when Voldemort started to rose he could be defeated. Instead Dumbledore produced sheeps that cannot cast a shield.
This story follows cannon with appropriate scenes replaced to show good Dumbledore who is blocked at every step.