A baby shampoo/mo;asses concoction is not a soil amendment although many people use it as a bad substitute fro properly amending the soil. The shampoo can help with water penetration, in small quantites, and the molasses can act as a short stimulant for the soil bacteria but it is not a replacement for organic matter in soil.
In larger quantities shampoos can be antibacterials.

WTF? We may be American but we aren't all stupid!

At the risk of simply sounding defensive, your one experience is the first time this has been reported. Then again, this is what forums are good for. In any case, my one experience is that the trees in my yard seem to be unaffected, at least I can't see any negative effects. In the other forums I participate in, no problems have been reported.

Molasses is, except for the impurities, a pure organic material. Once it is applied and washed in, it is organic matter in the soil. Besides being a carbohydrate food for soil microbes, it coats the soil particles with the hydrophilic solution which absorbs and holds moisture.

Almost nothing in the organic garden happens in less than 3 weeks. To lose an established tree overnight is surprisingly fast. Even if you removed all the soil and soaked the roots in soap I would be surprised if the tree would show any ill effects that fast.

Would it be possible to post pictures of the tree? Maybe something else is going on? Close up picture of the leaves would be useful.

Well, I was out taking some pictures and remembered that the neighbor down the street had a honey locust too that was planted the same time. They didn't spray the shampoo on their lawn, so I went to check out their tree. Sure enough, it is dying also. Looks exactly the same as ours. That is great news, as now I don't have to worry about my other trees, but now I am perplexed as to what the issue might be. Here are some pictures. Does anyone have any suggestions that might help out.

Talking to my wife and it turns out that she noticed a couple weeks back that there were a bunch of aphids on the tree. I have been noticing that there are a bunch of birds in the tree going after bugs, and many ladybugs too.

Could these plant bugs take out an entire tree that quick?

Aphids, as a rule, do not cause that kind of damage that quickly. Look closely at those trees to see if there might be one of the cankers that can kill Honey Locusts, talk with the people at your local office of your state universities Cooperative Extension Service since they will know if there are any diseases that would affect these trees in your area.