I think this is simple: Ginoboli is probably the biggest flopper of his generation. Officials are so used to his acting, I'm thinking the officials were of the mindset they weren't going to fall for it in that situation. It was a foul - this time. But Ginoboli and the Flopping Spurs have flopped, acted and baited officials into making calls so much during their era it finally backfired against them.
What isn't understandable is why the media covering the story and discussing it are ignoring this Spurs' history and its effects. The lead official had to address the no call and say it was missed ignoring a real possible reason why Ginoboli wouldn't get the call in that situation. This again reminds me of how the NBA seems like the WWE. Now there is drama and interest in the series.