People don't like getting their dogmas challenged, especially when it comes to their Fathers' sins.
His first sentence is reasonable. The rest of the comment is unhinged.
> The theory of an immigration of IA speaking Arya ("Aryan invasion") is simply seen as a means of British policy to justify their own intrusion into India and their subsequent colonial rule: in both cases, a "white race" was seen as subduing the local darker colored population.