SourceForge.net was once an excellent and trustworthy steward of Open Source software projects. It was predicted by some folks in the free software community that it would not always be the case, and alternatives like Savannah were maintained in order to act as a hedge against that concern. I believe it is more than reasonable to assume that github will change, and it would be downright dangerous to assume that we can rely on a profit-motivated corporation (even one as cool as github currently is) to remain a trustworthy repository forever.
So, sure, say nice things about github; I also think github is a good product, and I appreciate their free hosting for OSS projects. And, sure, you should use github if it provides value for you and you're willing to accept the price. But, don't ask me to trust they'll never change, because history indicates they will. It's probably also unfair to suggest that someone criticizing some valid concerns about github's current behavior, based on their own experience with Open Source projects hosted at github, are making "vicious accusations".