Yes, Patrick had her moments. And no, I'm not saying she was an elite rider in the top American classes, but she wasn't worse than a good amount of riders who are there. It's not like all of her good results, because she had some, were due to luck, and people often forget how incredibly often she was crashed out of the race by others. No, I'm not a fan of her, but "PR crap for ignorants" as answer to saying she had her moments is just ignorant in itself
De Silvestro had her moments as well, in between mostly hanging around at the back, accomplished more than Calderon and Flörsch (duh, she's rather much younger). Calderon has never really impressed me much, neither did Flörsch, although she is still young enough and has at least shown enough resilience and mental strength.
In the end, it's not like every team can just choose everyone to race for them. I didn't check why De Silvestro wasn't in the car, perhaps she had other obligations or just wasn't an option for Porsche for other reasons than just performance. If Porsche was looking specifically for a female driver, they may have tried her, but in the end it's still simply a matter of trying to get the strongest and De Silvestro isn't one of the strongest overall riders.
Calderon and Flörsch had nothing to do with Porsche at all, they were in LMP2 and so are just entirely out of this discussion anyway.