You can claim it's dumbassery all you want but the reality is that the ruling did make abortions legal and this is a move by the religious right to make them unavailable since they can't make them illegal. It's politically the next best thing and exactly why they are doing this.
Diluting this specific discussion(pp) by trying to talk about late term vs first trimester is stupid and does nothing to defend the defunding.
It's like you didn't even bother to read past "dumbassery"! I clearly explain why you're wrong, and you're just gonna keep on truckin' anyway! 
Would it help if I broke it down into pieces? Here's the first part:
First, regarding "an already fought supreme court case" - to which case are you referring? Roe v. Wade? You should actually read that opinion. Or, you can just read this very short summary of the opinion. https://www.law.cornell.edu/wex/roe_v._wade_1973. Suffice it to say, RvW only granted a right (not found in the Constitution of course - the justices just made it up) to unrestricted abortion in the first trimester. The court found that the states had increasingly compelling interests (stronger authority) to restrict abortion in the latter trimesters. Subsequent decisions have further muddied the waters, but even under current jurisprudence, there is no Constitutional right to unrestricted abortion.
Ok, so unrestricted abortion in the first trimester isn't going to be much more unavailable with PP defunded?
Maybe let's slow it down a little so you don't keep getting off course:
1. abortion is legal, right? First trimester, or whatever, there is legal abortion, right?
2. Shutting down the only place where abortions were available for a certain segment of the pop is making them mostly unavailable to that segment of the pop, right?
You keep trying to argue evil, but legality and limiting the availability of a service is what this should be all about. Evil has nothing to do with it.