I have used and have recommended nylabones since they first came out.
Every product, toy, food, marrow pipe bones, etc. can have dire consequences if used inappropriately, used in the "wrong" individual or not supervised.
Nylabones are made to have small pieces shred off during chewing. Some dogs aggressively chew and can break off large pieces that can potentially cause a problem. When the nylabone gets to a small enough piece some dogs try to swallow too large a piece of what's left.
In 40 years of practice I have not seen one case of Nylabones causing any problem other than bleeding gums or a cracked tooth due to too much chewing.
I guess my advice would be to watch your dog, supervise ANY chew object - bones, toys, treats, food until you are sure that their behavior with them will not lead to potential problems.
Nylabones in and of themselves are not the issue and blanket statements and warnings are a little misleading.
Doug, DVM