Yes, agree that it looks like a flashfire. Too many completely or partially unburned poles, too little spreading of fire.
I took a look to see if tents have flame retardant on them. It seems many/most don't due to sleeping inside among chemicals (essentially).
What they do often have on them - depending on the age of the tent - is different degrees of silicone. Some have silicone just outside, some have silicone inside and outside, primarily for water-proofing but it is also a flame retardant.
Being a bit of a camper, Russell's tent may not have been newish.
Silicone is difficult to ignite, and when it does burn it burns to a non-conductive ash. While burning, silicone does not give off toxic materials.
Why Use Silicone | Bellofram Silicones, Inc.