I entirely believe this. This is closer to their 10k pace than their 5k pace.
Literally just yesterday I did 6x1200, cutting evenly down from my 10k pace to my 5k pace, with 1:30 rest. I'm pretty sure I could have made it 8, definitely with the longer rest. And I live at higher than 5000 feet.
Obviously Farah and Rupp are doing these quite a bit faster than me, but in terms of rest and effort relative to maximal I think this is a reasonable workout. Especially when you take into account that Farah has been training at altitude for at least a couple of months every season, for years.
I'm actually surprised this gets such a strong reaction here. I think people overestimate the effects of altitude generally, and on intervals in particular.