If saying some crazy things means everything they say is wrong then you'd have to be a Christian Atheist once you put the bible and the complete works of Thomas Paine together.
It's not clear she's not just trolling against abortion. Is that what the article is? Because I looked up the author and she was disabled her entire life to to a genetic disease. It seems pretty reasonable to allow abortion for cases like this. Which is why it IS legal and even recommended in most of the western world.
I disagree with Harriet Johnson in at least a few cases, but the entire thrust of that piece and her argument within is "it's insane that people make judgements on my quality of life, without asking me, and say that I should not be born". You can make that argument and also believe that abortion is an appropriate tool for some cases.
Can you explain your opposition to Singer's views? I understand he argues in favor of legalising voluntary euthanasia, and increased abortion rights. As a non-religious person, his arguments generally seem quite rational to me, but I'm keen to understand more.