A large radar generates a lot of heat that is rather hard to hide.
For instance an AWACS aircraft could be targeted based on its radar emissions, but if shut down when the incoming missile is detected then the missile would still detect the heat signature of the target and home in on the turned off radar system.
The same would apply to ground based radar... I would suspect with a naval vessel the IR signature of the vessel against the water at a different temperature would allow engagement but again I suspect the engagement of the radar would result in trivial/ie not terminal damage as the radar arrays would be hit but the hull would not likely be penetrated.
Of course taking out the main radar array would leave the vessel vulnerable to attack from more conventional missiles.
Did Russia buy that version? I was under the impression that they did not.
Have heard all sorts of rumours... mostly from western sources about them not working. If they want them their new vessels all have UKSK launchers which are compatible with Onyx, Zircon, Calibr... which is the long range land attack version of Klub, and also the rocket powered torpedo delivering Klub model.. I don't see why they would not buy the anti ship subsonic and anti ship supersonic models of Klub too... there is talk of a supersonic anti ship missile in Russian service with a range of 1,500km... sounds like supersonic Klub to me. the whole purpose of a subsonic cruising stage and a supersonic terminal stage is maximum range and max effect in the terminal phase... it ticks all the boxes.