Thank you all very much for your kind and wise comments.
I told the "accidental breeder" tonight that I would
not be taking the pup.
I am very VERY sad, but my conscience just would not let me reward people for carelessness.
Especially since I accidentally heard some of the dog's human family say that now they should breed the dogs again.
My husband has been very supportive and says he thinks I made the right decision (he did not want to influence me so only listened to me until I decided). And the pup is very cute with a great personality, so I am sure the dog will find the right home soon.
Well, back to the drawing board of looking for a pup to train as a service dog. Sigh.
But at least three good things came out of this. First, I started walking again (in preparations for walking a dog) which is very good for my disability. Secondly, the whole experience made me decide to become more assertive about finding the right dog, asking the tough questions, and not just waiting for any dog to come along. And finally, I met some other responsible dog owners locally, including a yorkie person just around the corner from me whom I can talk to!
Thanks again, everyone, for talking with me today. You all made a world of difference to me. You really helped!