The entire point is that he didn't think! He made a mistake. It happens. He saw the joke he wanted to make, made it and then realised how it could be perceived, though "oh ****, should have realised" and removed it.
I have absolutely no doubt that we have all said things that were open to be misinterpreted, come out wrong or had to be apologised for. Its a sad state of affairs where the default situation has become "don't care, you should have know better, you are fired" rather than actually accepting that people sometimes make genuine mistakes.