i have to say i had her down as a loon the first time i read it as well.
and anyone reading the article (even in the dm) should be aware that the boy wasn't stuck at all, he climbed the tree to hide and was refusing to come down at the end of break time.
i'd have left him there as well.
and watched. no way would i have started trying to get him down - recipe for disaster. ask him if he's stuck. ask him to come down. then back off.
i suspect he saw the loon woman coming along the road and decided he was bored and would like to come down after all. at which point the school staff, nutcase passer-by and boy all converged and she started accusing them of negligence and shouting.
i would have called the police as well i think, particularly if she was being verbally or physically aggressive.
interesting that she's supposed to have accessed the school grounds inappropriately before though... did not get that from the dm lol.
i'd def have been calling the police in that situation.