It may not be the best advertising photo, but I hardly think 'poor horse'. The bit isn't being cranked and we can't see the rider, so you can't assume he's being ridden rough. Could just be a bad picture, or the horse just got bit by a fly or the horse is a cranky horse, or ..... you get the point.
I think the horse is either on the way to get mad, or was concentrating hard and listening, maybe somewhat worried as others noted.
Without knowing more, seeing where that picture came from and what developed the next second, I would say it is not enough information there to make a definite call.
When a horse is clearly mad, the ears are more back, the nose more wrinkled, the eye hooded.
The way his upper lip is sticking out, I would say, right there, he shows some strain as he seems to be making an effort and trying hard, but can't say where that is going, not knowing the horse and rider.
If the hand gives softening, he may relax his face and start flopping his ears in a few steps.
If the leg/seat keeps pressure with little relief in front, he may well put his ears back, ring his tail and look annoyed to mad.
I have no way of telling from that moment.
I wonder if the layout people were just looking for a certain photo that allowed a lot of text to be in a column on the side. It's certainly a narrow profile picture - and there's no way of knowing if the employees know jack about horses. You'd think the horsey company who paid for the ad would check it out before paying for it, though. Then again, isn't there a dewormer ad showing a rider with his spurs on upside down?
Brothers and sisters, I bid you beware
Of giving your heart to a dog to tear.
Could be a graphic designer who just has no clue about horses, or advertisements created by a hired firm and not in-house. I can't tell you how often I have, for example, seen someone get professional photos (senior, engagement, whatever) done with their horse in them and it was very obvious that the photographer, while otherwise excellent, didn't understand horse expressions or body language.