Assigning abortion a 30% chance of being murder is ridiculous, and depends on a fallacy that is also used to argue for vegetarianism: people who are asked to estimate the probability of something with a low probability will usually pick one that falls in a certain range, regardless of whether it is a good estimate. And other people who look at that number will say "yup, looks like a small probability to me", even if it really isn't small enough. I don't usually see it done with numbers as high as 30%, but even 5% would be far too high. A 5% chance that abortion is murder does mean you should avoid abortion. A 5% chance that chickens are like people makes a non-vegetarian into a statistical mass murderer. But the only reason to pick 5% instead of 0.000001% is that few people will estimate something as 0.000001%, regardless of its actual value.