they should be nervous. I have friends going and Im going to recommend they leave their Pats jerseys behind. Its not worth it. Even if 98% of people are normal and respectful, you are going to have a certain % frothing at the mouth and unreasonable.
I have no desire to attend a Bills away game in a place like in the Northeast or San Fran, etc... Maybe like Jacksonville or Miami it would be possible... but nothing good would come out of marching into Lincoln Financial Field with a Moats Bills jersey