I think that the poster is implying that many of the same people who describe themselves as Pro-Life also support the death penalty, are huge supporters of having a huge U.S. military (much bigger than needed for territorial defense, so obviously it is going to be used for other things), and are often loudly pro-gun (the argument here is that a gun is offensive, not defensive, so anti-life). Squaring these positions with the description Pro-Life can be a little odd.

While it is a little unfair to over-simplify this way, many Trump supporters are Pro-Life, and those same people seemed to enjoy and support his recent comments: "Very simply: If you rob a store, you can fully expect to be shot as you are leaving that store".

You can make a position that the thieves he was talking about have given up their right to life in a way that a fetus can not, but I think there is also an argument that this view can not be squared with a Pro-Life designation. I find my own opinion somewhere in the middle, but closer to the latter.

Elaborating on that is the red herring. We shouldn't have to elaborate on that, it doesn't need to be the central argument here.

while I do think the poster is a bit of a jackass, it's obvious they meant ending the life of a fetus and not ending the life of a person in general.

We can take them for what they meant rather than what they said.