This type of activity helped elect Nixon in 1968.
Nixon was helped enormously by: Lyndon Johnson renouncing a second term, the Democrats’ utter confusion following the MLK & RFK assassinations, the Chicago riots, and the anticlimactic nomination of LBJ’s hapless veep Hubert Humphrey.
So much better that Nixon won but consider the unique clash of events in ‘68. If the leftwing crazies do a Chicago on the Democrat recoronation of Obama in Charlotte, most who pay taxes will opt for the conventionality of Romney.
But then let’s do some math. Chicago ‘68 didn’t have an incumbent POTUS in the convention hall. Charlotte NC will be under full Secret Service lockdown and that will create all kinds of resentment having nothing to do with politics.
Voters may decide that ideology aside, they don’t want to give four more years to someone whose personal style is already that of a dictator.