I really cannot relate to you as a human being based on that statement alone. If you are from Buffalo and you have any soul you will be a Bills fan. If you say you are a Bills fan and a fan of another team, then in my opinion you are not a Bills fan and you probably are the type of person who is cruel to children and animals. Whenever I meet a new person from Buffalo the first thing I ask them is if they are a Bills fan. If they're not, well I honestly want nothing to do with them.
The answer to your question is that you should be fine with Jets stuff on as long as you don't act like an idiot and provoke any drunk Bills fans.