Everyone always forgets about the uplink.
It's much easier to attack a base station or multiple bs and very difficult to detect if done right, and has size of matchbox. For a high power downlink sync channel, that would be difficult and not very effective methinks, it needs too many things to work right, like good coverage, poor signal from real network, big antennas, high power=good location for a base site. Wipe out a city? hardly.