The "research" the article is referring to seems to be a meta analysis. I don't have time to look at the full text right now, but I have a feeling there is a lot of publication bias and anthropomorphization. It's certainly worth looking more carefully at when time allows though. I also suspect that what is right for one species of snake may not be for all, and that time outside the enclosure should be taken into account. For example, Kevin at NERD has a "playpen" of sorts for his giant snakes to stretch out and get exercise, though he probably should still provide his retics with more vertical size and things to climb on in the enclosure, and the one playpen couldn't be possibly used often enough for the amount of snakes he has.

I'm not sure why a snake would need to stretch out their full length all in one direction at the same time. I try to go with the LxW > length of snake rule. But I am certainly willing to be open minded and change things if the evidence is sufficient.