But a huge decrease in the volume of mathematical and scientific output. If anything astronomy was picked up by the Mongol invaders (Ulug Beg). Tyson is far from being the only one pointing to Al-Ghazali as a big influence in the decline of Islamic learning. Toby Huff takes a very similar position and with a lot more evidence. That said, the Mongol destruction of the Bayt Al-Hikma was certainly another factor.This is a bit of an overstatement. Ghazahli's 'Incoherence of the philosophers' is often given a lot of credit for reversing the Islamic attitude to science (in Cosmos, Neil Tyson practically blames Ghazali for single handedly precipitating the ending of the Golden Age), but it actually led to an increase in philosophical output.
We see these repressive attitudes frequently at times of threat and instability when there is a strong drive for ideological conformity.
Whether this is post-reformation, 5th C Christianity with disputes over monophysitism/Arianism/etc. combined with the decline of the Western Roman Empire, and plague and Wars with Persia affecting the Eastern part. Also in the Islamic Empire(s) in the period that included in the Mongol invasions.
This seems to be a pretty common future of human group dynamics.
Unfortunately, I tend to agree here.