I've been reading his "manifesto" and it seems well researched at first but once you take a look at some of the sources...
His knowledge of Arab-Islamic history is really light. Either that he's chosen to disregard it and lie for his agenda.
From a section titled "The First Major Wave of Jihad: the Arabs, 622-750 AD". The section right after it is titled "The Second Major Wave of Jihad: the Turks, 1071-1683 AD"
This first wave of jihad engulfed much of the Byzantine, Visigothic, Frankish, and Persian Empires and left the newborn Islamic Empire controlling territory from Southern France, south through Spain, east across North Africa to India, and north to Russia. Early in the second millennium AD, the Mongol invasion from the east greatly weakened the Islamic Empire and ended Arab predominance therein.
The Mongols didn't end Muslim expansion. They also don't fit into the time frame he put them in. Muslim expansion into Europe was stopped by internal war within the Umayyad caliphate as well as a powerful Frankish and Greek Empires. The Mongols had nothing to do with halting the Muslims armies advance into Europe. The Mongols first started warfare with the remnants of the Umayyad caliphate in the early 13th century when Genghis Khan conquered Iran. By this time though the Umayyad Caliphate was gone by about 400 years. It was replaced by the Abbasid caliphate which imploded into the Fatimid Caliphate and a bunch of other kingdoms spread across the ME. The Mongols did destroy the last caliphate that could claim direct descent from Mohammad in the mid 13th century when they invaded Baghdad. But by that time though, the Abbasid caliphate was reduced to only holding Baghdad and some land around it in modern day Iraq.
tl;dr The Mongols didn't weaken shit. French, Germans, Greeks, and Arabs stopped Muslim expansion.
The guy is obviously not dumb. It wouldn't surprise me if he has a genius level IQ. I'm just disappointed he put more planning into the attack than he did researching the thing he is so much against.
I think I may need a hobby...