[soldarnal]

Nobody has the right to assemble on someone else's private property. Moreover, even with public property, the right to peacefully assemble seems to be not without restraint. For instance, the courts have upheld laws creating "buffer zones" for abortion clinic protests. Likewise, a lot of cities require you to get a permit for demonstration purposes.

[fnid2]

It was property rented by the government for the event and so it was therefore temporarily public property and a public event.