I'm not sure about FZ, but on some older NG the AP will disconnect at TOGA press on a dual channel approach unless the self test is complete, this starts at 1500RA and usually completes at about 1200RA.
They were flying a Cat 1 approach which would almost certainly have been single channel so the go-around would be manually flown. Because of the weight the N1's would have driven to around 80% N1 (or maybe less) on TOGA press to give a sensible rate-of-climb; what I have seen quite regularly in the sim is when 'check GA thrust' is called the PM increases thrust to full GA N1 which increases workload and required scan rate significantly. Couple this second pitch up effect with the awful conditions then I think there is a good chance as already mentioned of some sort of somatogravic illusions occurring.
Lots of speculation here including mine; sufficed to say that the 737 (all variants) can be a handful in a go-around and it's about time this became a mandatory item on a proficiency check.