Nobody's saying they wouldn't just reflash it at the hospital. Replacing a pacemaker requires surgery, which is why they're externally programmable in the first place.

One of the things I've learned in life is that We're All Just Folk. There's no magical divinely-inspired programmer out there creating firmware for your pacemaker. The difference between him and me is process, and little else. If I'm given access to the same testing processes they use as part of the open source package, I see no reason to believe my code is going to be worse than anybody else's. Sure, I'd think twice before installing it, but in some sense that's irrational; I should think twice before anything like that because We're All Just Folk, and it's just some guys writing all the firmware we all depend on.

In some ways, it's best not to think too hard about this.

Whether or not a pacemaker is running free open source software is independant of whether or not a person can flash their own version of the software to it.

If it were open source you, or anyone who was fitted with the pacemaker could look at the rules that control it.

Making _anything_ visible and open to criticism instantly makes its creators more accountable and adds pressure for them to try and be responsible.

Oh come on, free software does not imply an open source development model and vice versa. You could very well have the software developed by a professional team and release it as free software.