[golem14]

It probably matters if the park, or the rented sub-venue is a public place or not.

Local laws also matter.

In the US, getting someone removed from a public event without or with fabricated cause is likely to cause problems down the road, as the removed people might be likely to win lawsuits.

Belgium has probably - like the rest of the EUb - far weaker freedom of speech protections,

But IANAL, and just a second rate, third hand armchair commentator.