This isn't always the case, but you're right it's pretty odd to go through with this case on such shaky ground. It's almost surely because they couldn't find an

This isn't always the case, but you're right it's pretty odd to go through with this case on such shaky ground. It's almost surely because they couldn't find anyone better, many of these cases wait until you find the perfect plantiff and it can take a lot of time/money searching. They would have to be in a very sympathetic court to get the ruling they want given the harm they're trying to demonstrate. It makes no sense that medical procedures should be banned because other doctors might be asked to treat complications. That's how literally every medical intervention works.