You don't why that happened, so you just assume "treachery" without investigating.
Because, apparently, your baseline assumption is that highly complex war plans always unfold precisely as hoped for and if they don't then there must have been a conspiracy.
Have you heard of a general named Napoleon Bonaparte?
My reading on the subject of Omaha was simply a matter of bombers on that beach having poor siting due to some overcast and that naval bombardment also suffered from not being able to visualize targets once they began shelling because of the way prevailing winds blew all the smoke and dust in such a way that screened the targets.
A great story is the USS Texas which, seeing how badly the men on the beach were doing, sailed in much closer than they normally would so they could get good visuals on the pillboxes. Their shelling, while almost running aground, played a big role in saving the day from utter disaster.
This is from memory of a lot of reading over years, so please forgive me if the details are not quite right. Best of my recollection, though.
This is from Dick Morris .com and is from a biography of Eisenhower. General Bradley opted out of using heavy tanks, instead using smaller types which almost all did not make it to shore to help the troops being slaughtered. The GI’s had a ridiculous 68 lbs in their packs, as compared to the British 20 lbs, causing many of them to drown or be killed by the slower movement with all that weight. The other beach landings were pounded for 4 hours, wiping out a lot of the defenses, Omaha was hit for about 40 minutes. If they saw an issue with targeting, they should have been ordered to move their asses up closer before the landing. They also launched the landing crafts from a ridiculous 12 miles rather than 7 which caused more sea sickness and a not sharp trooper when he finally made it to the beach. And, to top it all off, the used a frontal assault, rather than a flanking one , when they knew from previous engagements, that it was much more difficult. I know it is easy for us to point this out so far away from the actual battle, but I think it is obvious that Bradley really screwed up Omaha and those poor men that were mowed down for several hours had to pay an awful price. I just hope they all are in heaven now and would think that they are.