On one special occasion like that, I don’t see any harm in it.
It wouldn’t bring others into town on a long standing basis.
Most people would not similarly let the government restrict fire arms or speech. They would consider it a gross violation of the amendments containing these freedoms.
And if every church in the country were to do something like this, then there wouldn't be a problem of bringing in people from other areas, would there?
Christians are commanded to go out and feed the poor. Parks are gathering places for the general public and places where poor people hang out. There should be no restrictions on churches feeding the poor in public parks, just as there are no restrictions on people feeding themselves in the same parks.