SWMAP is correct, in my opinion:

"...If people behaved as they did when crowds would sleep peacefully on Belle Isle on hot summer nights [[my grandmother often talked about taking her sleepless babies there) then likely there woundn't be such a policy..."

I slept peacefully on the Belle Isle beach many times, decades ago.

It is sad that one must cross the river to enjoy the riverfront, undisturbed, late at night.