They can not have them back...

Even if they wanted them.
You need to see the larger picture iddee.
1) It took 50 years for them to achieve a strain of AHB worth keeping.
2) AHB eliminates all other genetics in any given area.
Based on the above, you can actually see that AHB may be worth propagating or controlling from a commercial basis. But it's not like those in south America have a choice of keeping other type bees. You keep all AHB out or you keep nothing but AHB's. It's that simple.
In the world of gentics, you want diversity and options. When you limit yourself to one strain of bee, you also set yourself up to allow one viral or bacterial outbreak to wipe them out. Right now, in any given area, you can keep italians, carni, russians, in the same yard. Both independently and as hybrids. But having those different strains allows the bee industry as a whole to select for various qualities, certain genetics to handle certain disease, etc.
Once AHB are in an area, all other bee strains and genetics are systematically eliminated. And that is both domestic and feral stock. Who knows which strain may be better to deal with future viral mutations? Having as much of a diverse genetic pool to draw from is the best option we have.
I think there are many qualities that we may want from AHB. And with the genome, and future ability to select DNA elements, and even suppress others, we will no doubt benefit from AHB. But that is for the future.
What AHB are doing now, is eliminating or diminishing the genetic pool, limiting beekeepers due to zoning and regulation, etc.
To say that south American beekeepers do not want EHB's, is a bit misleading. They do not want them, in a twisted way of promoting their own destiny, since they can not keep EHB even if they wanted. And to bring in EHB's would allow hybridization, and destroy everything they have acheived in the past 50 years.
When ever you limit genetic selection or only propogate one or two strains of anything, nature will bite you in the butt. Why did millions die in the potato famine? Becuase leading up to it, farming focused on planting only two types of potatoes. Both susceptable to the disease. Other types of potatoes were known, and many were resistant. But people only saw the benefits of one type of potatoes and propogated this one line and it accounted for over 95% of all the potatoe production. And a single disease wiped out that stock, millions died, and a valuable lesson was learned.
Having one bee strain will allow the same type scenario to play out. Nature keep bee strains seperate by barriers such as oceans, mountains, etc. Man breaks these barriers down, and allows unnatural events to happen. Some think AHB may be the answer to many problems. But due to what you lose (genetics), and by placing all your eggs in the same basket, you set yourself up for a tremendous fall.