I think that they are being instructed how to react by someone higher up in the power structure. The boss of that someone probably occupies 1600 Pennsylvania Avenue, Washington D.C.
It's been disturbing since the first protests, when identical strategies of closing major highways happened all across the US. Outside agitators were leading mostly stupid suburban college kids and whacked-out fake liberals, and police everywhere let it happen.
Somebody way up the power struggle seems to want chaos in the US. At this point, it's gotten old, and those protesting should be jailed, fined, and given criminal records.
JMHO