Yes, they can digest it, there are lots of horses who have proved that. Maybe not as efficiently as if ground, but you can feed a little more, and since whole flax is really cheap when you by “animal” flax in the big plain brown bags, feeding a bit more is still cheap.
I am a minimalist, stabilized to me equals additives. I would much rather feed the real deal without the chemical experiment.
If you consider mixed tocopherols, the most common stabilizer/preservative in things like this, a “chemical experiment”, then ok
Not everything is preserved/stabilized with BHA
Also, don’t forget that not all “ground” flax is actually ground. Triple Crown Naturals Golden Ground Flax is actually cold-sliced, no grinding, so is still really stable, up to about 2 years. I’m sure some other “ground” flax products are done the same way.
So no “chemical experimentation” is needed to keep things fresh 
Plus the goopy consistency of flax when wet, along with the extra fiber, must be really good for guts.
Flax isn’t very good at pulling sand out of the gut, despite the mucilage trait (the goop/slime), and the fiber is totally insignificant in the context of a horse.
I would definitely grind, or buy ground, flax for this. It’s not that it would be a health problem to feed, it would just be nice for at least a reasonable amount of flax to have contact with good grinding surfaces
[quote]My understanding (after doing some reading last night) is that they need to chew the seeds a bit to sort of bust them open to get the nutrients out of the seeds - that hind gut digestion of full intact seeds release some fat and a few nutrients, but not the Omega 3 - for that you need to grind the flaxseed.[quote]
Don’t forget the stomach pH of as low as 2-ish is really good at breaking down much of the hulls