It wasnt his property, you cant burn something that isnt yours and call it free speech, unforunetly, this IS arson. Although no doubt had it been like a Madagascar flag nothing would have come of it.
The owners of the flag abandoned the flag on the flagpole he was responsible for. The first time they put it up, he removed it and returned it to them. Then as he left, they put it up again.
He then removed it and disposed of it.