From a post to Baen's Bar Snerkers Only dated November 16, 2006:

Keyhole platform survivability

    Okay, one of the (many) things built into the Keyhole platforms (which do deploy beyond the boundaries of the wedges) are extraordinarily powerful EW capabilities and several different layers of active and passive defenses. Moreover, when the RMN developed the system, it also developed doctrines to defend the platforms.

    One reason for the multiplicity of Keyhole platforms -- that is, one reason they are fitted to all of the new SD(P)s rather than just to one or two ships per squadron -- is that doctrine has always called for them to "go quiet" to confuse incoming missiles. The FTL links of the Keyhole II platform are the only one which can easily be picked out of the background of ships' wedges, active targeting systems, and the general hell raised by EW/ECM, not to mention the confusion of missile wedges going off in all directions at once.

    Because of this, the platforms are simply nondetectable when they are not radiating commands to Apollo. That is, in "Receive mode," they have no betraying signatures. In "Transmit mode" they are readily detectable, but they handle most all of their transmissions in very tight windows, then go dark again. Moreover, whenever more than one podlayer with the system are involved, they share command channels and the "active" platform jumps frequently and randomly. That is, Ship A may transmit the commands to all Apollo drones in one "active" window, while Ship H will transmit the next series of commands, Ship E transmits the third, etc.

    The platforms themselves are also capable of movement. By this I mean that the tractors controlling them can shift their positions relatively quickly, which can include simply moving them a few hundred klicks astern or ahead or sucking them back inside the wedge's protection. The squadron tac officer can control which platform is active and deliberately use one of them to suck in enemy fire, then zip it back inside the wedge once the other side's missiles are committed while he brings a completely different platform on line to take over control of the engagement.

    In addition, the platforms have the equivalent of the "buckler" mounted in them (I did tell you they were big, didn't I?). If a lot of fire seems to be coming in on one of them, the tac officers also have the option of turning it to face the incoming and bringing up the buckler. This may drive that particular platform off the air until the buckler comes back down, but it also interposes a sudden passive defense the missiles had no idea was coming. Loss of lock is far more common than not in a case like that, and even the ones which maintain lock find their effectiveness greatly reduced.

    The EW systems in a single ship's platforms also have the capacity to do the sort of "jingle-jangle" that we've seen ships doing with deployed decoys in the past. By jumping back and forth between the platforms while transmitting orders, it's actually possible to convince missile seekers that the commands are coming from a single platform located midway between the two actual platforms… which brings them in directly on the deploying ship's wedge.

    And, finally, missile defense doctrine has been modified to make defending the platforms a very high priority. A percentage of CM fire is normally reserved specifically for defending the platforms, and the platforms themselves are heavily fitted with point defense clusters. In effect, they augment their mother ship's active defenses while simultaneously defending themselves against incoming missiles. Remember that laser clusters are designed to defeat missiles before they reach effective stand off range for a laser head. If the missile is killed before it detonates, no one really cares whether it was aimed at Keyhole or at the mother ship. And it would be extraordinarily difficult to get a missile close enough to take out a Keyhole platform with a "proximity" nuke.

    I am not saying that ships will not lose Keyholes, nor am I saying that they are magically invulnerable to missile fire. Another reason for the multiplicity of them in squadrons is to have backups available to take over for destroyed platforms, after all. But they are nowhere near so vulnerable as some people seem to be assuming.