She may have imported the dog if the lamplighter dogs are back in the pedigree. I am pretty certain that Fonzi was sold to a breeder in Europe so prehaps thats how she got that line?
It is not unheard of for a show male or a male from a show line to be 6.5 lbs thou and used for breeding.
As for the vet he/she wouldn't have any final decision on wether they spayed their female or not. He/She can give their opinion but the final decision is the owners no matter how well the vet likes it or not.
And to spay a female at the same time as a C-section is dangerous as she is more apt to bleed out. So I would only suggest that if it was a lifesaving decision, I would wait until she has had time to recoop and then have her spayed later but she should have never been bred the first time being that small.
TJ