There seems to be more to the story. The young man seems to have brought along an amplifier to make his “speech” heard far and wide. If I were in a park with my grandkids I wouldn’t want a boombox of any sort blaring away nearby.
Yet people are allowed to blast their music (a form of speech) and left alone for the most part.
So if he talks too loudly and disturbs your space he should be arrested? Is that your right under the Constitution? Which article or amendment would cover that?