Constantine hasn't been straight washed. They just haven't addressed him being bisexual yet. They have left hints to it the same way they have shown him smoking by circumventing the no smoking policy.

I don’t know if that’s entirely correct as some of the things said by people working on the show seemed to indicate he would not be shown as bi.

However, I don’t watch much television, I don’t keep up with it. So I really should stop answering tv questions.