His abstain from penicillin fallacy illustration is just another version of the JWs' abstain from alcohol fallacy illustration. As you rightfully pointed out the very critical difference between the why of abstention from blood and the why of abstention from penicillin, is conveniently omitted because those very critical differences in the whys causes the comparison to fall flat on its face for the fallacy that it is.
Another interesting point is this: JWs apply the command to abstain from blood to blood transfusions by equating a blood transfusion with the eating of blood. What's their basis for equating the two? Since feeding can be done intravenously as in the case of very ill patients, they reason, then the administering of blood can be compared to such feeding since it too is done intravenously. I don't know the technical term for this kind of fallacy, but it's basically the fallacy of equating two practices (transfusions and feeding) based on the fact that they share a common action (intravenous administration of a substance).
This is a very interesting fallacy that makes hypocrites out of the JWs. Why? Because if they apply this flawed reasoning consistently, they should also be abstaining from invasive gynecological examinations. You see, Acts 15 also says to "abstain from ... fornication" - a practice which often involves inserting an object into the vagina. So by the JWs' fallacy of equating two practices based on a common action, both practices (fornication and invasive gynecological exams) share the common action of inserting an object into the vagina. Therefore Watchtower should regard such gyn exams as a form of fornication and instruct JWs to refuse them.
Of course, if you tell a JW that abstaining from fornication should apply to gyn exams based on their own fallacy of equating two practices based on a common action, the JW would be quick to say you're being ridiculous and proceed to show you how the two are not the same. He might point out the different motives and objectives between the two actions ... and then you can take his own reasoning and turn it around to the blood issue to show him how the organization's position of equating blood transfusions with the eating of blood is just as ridiculous.