I read up a bit on the meshtastic broadcast algorithm and you are right, 1 would only work if the node in question is the only one in range that could reach the target, so in real life, not so much of an issue.

But it would be pretty simple to flood the network with garbage thus denying the service to anyone else. Would be even simpler than jamming, because you can abuse other nodes to rebroadcast your jams far beyond your reach.