Well, being in the U.S. military and having experience with that I'll have to take issue with that comment as the government does not always purchase the best, they purchase the best value for the mission requirements. I have plenty of experience with paying government contracts, and fiscal law as well to know this for a fact.
I do believe that regardless of the thickness of the anodizing, the black dye does indeed lend a certain amount of overall weakness to the final finish.
In layman's terms I think you have to make black dye type III finish thicker in order to make it stronger than type III natural finish. It only seems logical.
The government buys from the lowest bidder (or the one with compromising photos of a senator). The entire reason for military specification is so that the lowest bidder builds whatever it is to the specs on the drawing so that corners don't get cut. for
MIL-A-8625 Type III Class 1 and 2 the thickness should be 2 mils. I've always said that Milspec seems to mean more to civilians than it does to anyone actually serving and means less to Marines because we never got issued anything until the army wore it out. But the spec is there so that more than one company can produce the same gear.
What you are failing to realize that it isn't the dye that is making the anodizing weak, it is the company cutting corners on the anodizing thickness which is much easier to hide when black dye is used. If you are making this comparison based on Chinese lights that claim to have MIL-A-8635 Type III Class 2, which states a thickness of 2 mills, then you are doing yourself a disservice.
There is a difference in saying Type III class 2 and simply saying hard anodized type III, or even Military type II HA. That's marketing. Most lights don't have a 2 mil thickness. Compare the anodize on an Elzetta, Gemtech suppressor, HDS, or true 2 mil thickness HA on a receiver. Cheap products have thin anodizing as a way to cut corners, and class 2 helps to hide this, but if done properly to the actual MIL-A-8625 Type III Class 2, it will be 2 mils thick, which most of the cheap and even the not so cheap lights are not actually doing. Considering the dishonesty in output from manufacturers, do you really think they are being honest about the anodizing as well? That would be pretty naive.