From the argument, it seems that the violation of the conditions in itself is not trespassing. Trespassing is staying after the conditions were violated. Since the person was promptly removed, it is very hard to argue that they trespassed.
You could argue that if he violated the conditions and then made to leave immediately after then that was not trespass. I could see it going the other way too, though, if he entered the property with intent to violate the conditions (the flag was no accidental, after all). But if he knowingly violated the conditions and remained and/or resisted attempts to make him leave, that would still be trespass.
Not a lawyer.
From the argument, it seems that the violation of the conditions in itself is not trespassing. Trespassing is staying after the conditions were violated. Since the person was promptly removed, it is very hard to argue that they trespassed.
You could argue that if he violated the conditions and then made to leave immediately after then that was not trespass. I could see it going the other way too, though, if he entered the property with intent to violate the conditions (the flag was no accidental, after all). But if he knowingly violated the conditions and remained and/or resisted attempts to make him leave, that would still be trespass.