Unwise/Unnecessary to Counterprotest in Proximity to Protesters
It seems to me that it is both unwise and unnecessary to have counter-protests on the same day at the same time in the same vicinity of a protest! Governments should issue permits to both requesting sides; but, permits should not be issued in a way in which interference and conflict is likely to occur.
It seems that protest against a protest could be effectively done on another day in proximity to the protest of which one is against, If done on the same day where there is an overlapping timeframe then it should at least be done at a location far enough away from the protest that physical interference does not occur.
When government authorities allow protesters and counterprotesters to encounter each other there is a risk that violence will occur. In Charlottesville, violence did occur.
In Dallas (South Dallas), Texas in April 2016 there was a protest reportedly against a Nation of Islam Mosque by a group composed of mostly black people showed up. Both sides wore protected gear and were armed. It ended peacefully when the protesters decided to leave. So you see you just don’t know how it will end when authorities allow protesters and counterprotesters to engage each other.
Now if the protesters march into a residential neighborhood with the clear intention of mentally and/or physically intimidating or harassing someone then counteraction is appropriate. This may also apply to areas other than residential neighborhoods. But if anyone is allowed to rally in a public area such as a park then everyone should be allowed to rally without interference/intimidation by others in disagreement with them. This means those in disagreement should rally in the public area on a different day or at a different time.