None of those sentences is a correct use of the word 'straddle'. For me, the most obvious word to use in those sentences would be 'avoid'. If you avoid a topic, you find ways of not talking about it. As for the word 'straddle', it describes a physical movement or position, where you have your legs on either side of something. For example, you straddle a horse to ride it. You cannot use this word in a figurative sense to refer to problems or topics. I think you must be mistranslating a Spanish word. Or maybe a Klingon word?

think of straddle as standing with one foot on either side of the barb wire fence-- no matter which way you move it is going to hurt. Politicians do this by promising stuff to people on both sides of issues.