As the adage goes: with power comes responsibility. If you want to stud your dog out, do so…it is your dog. That being said I do believe it’s important that you wait until such time you are able to discern whether or not your dog is healthy, free from genetic defects, and follows the standard of a Yorkshire Terrier. You can neuter any time, but once done it cannot be undone.
I would like to also think you would be careful to what Yorkie you studded your dog out too…is that dog also healthy, free of genetic defects, and to standard? Regardless of how “perfect” your dog may be if bred to a substandard Yorkie the pups have a greater likelihood of being less than desirable, and a cycle of substandard Yorkies are possibly perpetuated as a result. And I believe this is what many are (rightfully) concerned about.
A breeder, reputable or not, cannot keep every puppy, breed worthy or not. After all, if a reputable breeder’s dogs are so good (generation after generation) the majority of the puppies produced are going to be equally as good (law of averages), thus there are many breed worthy puppies being sold all the time. There is no reason based on what information you gave to assume your dog is not as breed worthy as the next. As previously stated only you and your breeder know what you have, but you could certainly have your dog assessed by several others with experience in the breed (unknown to each other/listen for common statements). If it turns out your dog is not breed worthy then you should consider neutering.
It’s also possible your breeder may have been heartbroken over the loss of the mother dog and wasn’t seeing the whole picture regarding just how much potential your pup may have, thus it is up to you to wait and see before making decisions regarding its breeding, or not, future.
Death from anesthesia could be from several things, including too much given. The fact the mother needed a c-section seems like it might be more of a concern than the cause of death.