Whether a factor or not, it’s a good reminder of the need to be in trim at the final approach speed and not to trim during the flare.
Safetypee, not a factor in the 777.
It looks to me, also, that the reversers are deployed and that is definitely a commitment to stay on the ground according to Boeing and, a little bird tells me, JAL. Even allowing for his very questionable decision, Captain-san then compounds the problem with a totally ridiculous pitch rate and one I would have bet a LOT of money on the outcome being a tail scrape. No power/pitch coupling problems, just a totally ham-fisted PF and very poor decision maker
IF it turns out the reversers were as they appear on the video.