Let's give him the most benefit of the doubt possible. He comes from one of the worst states in the nation with regards to gun rights abuse and has not been a vocal critic of the state's gun policies. Despite the strict anti gun policies in his state, gun violence in his cities remains a serious problem and he has not been a vocal opponent of the argument that this is because NJ doesn't have strict enough gun laws. So assume Christy believes in the Second Amendment protections of our gun rights. His entire experience is informed by extremely strong anti gun laws, a population that is largely supportive of such laws, and having to constantly be aware of and cater to a voting majority that is generally liberal. He will simply not be a strong advocate for gun rights and will likely gravitate towards "compromise" positions on things like universal background checks, magazine restrictions and other things that he will likely see as "reasonable" (AWB entirely possible).