Much of that is plainly incorrect, and I would urge readers to beware of someone making unfounded claims about historical fact that are difficult to verify as if those were sound support of their arguments. The most useful arguments are ones that demonstrate self-evident logic and don’t assume tenuous claims like “That's exactly how the Umayyad caliphate took over chunk after chunk of Spain” and “It's called taqqiya” as fact.

The Umayyad Caliphate conquered Spain mostly through conventional warfare, like in almost every conquest in history. Military force is what gives a conquest the impetus and the conditions to succeed, and it is something that these migrant waves are categorically unconnected with. Cultural subversion is typical of a conquest, but it is not the defining feature.

Taqiya is about avoiding persecution, not subverting and replacing an indigenous culture. It is not a military doctrine that Muslims are trained to follow; it is a philosophy and practice for surviving a hostile environment.