No. It is a fundamental data problem relating to sensor accuracy/precision. They are called "suicide burns" for a reason. Start the burn too late and you run out of time and smash into the ground. Start too early and you run out of fuel and smash into the ground. So you need a sensor with error bars similar to your safety window for the planned burn.
Let's say you need to start the burn within a +/-10m box to come to a stop 1 to 21m above the moon surface. You want a sensor with something at least 10m precision but preferably more like 1m. That would be the radar. But then say you have something like a GPS with +/-100m precision. Does that help? Your safe window is somewhere inside that 200m but you cannot be sure where until the radar comes online. So do you use the +/-100m info from the GPS? Do you maneuver to center yourself inside its error bars? All you can be sure of is that you are somewhere within that 200m and are 95% sure you are not within the 10m window. So you make a maneuver anyway. Are you now in any better an information position? No. You are still somewhere in the 200m box and are still very likely outside the 10m box. Heck, you might have been inside the 10m box and just moved yourself out of it. You just wasted fuel. The only logical thing to do is to ignore the GPS and wait for the better/actionable information from the radar. The GPS may give you a warm fuzzy but it doesn't actually help when you only have one shot at the burn.
(This problem is mirrored in areas like missile guidance. Running parallel sensors on a missile sounds like a good idea but in reality leads to confusion, wasted energy/range and reduced chance of getting to the target.)
Not that I doubt your conclusions necessarily, but isn't this what sensor fusion is for? You can cast it as sensor "selection", which is fine, but given two sensors that show 10/1 accuracy (variance 100:1), and the estimates are consistent, I don't know why you'd expect it to have divergent results. (Am I understanding the problem here?). Your pos/alt is still measurable but with big old error bars until the precise sensors kick in.
You can only fuse sensors that are online. In the recent crashes the radar wasn't. The point is that you cannot swap out a high accuracy sensor, not when doing suicide burns with zero margin.
Worth noting too that your original, pre-LPS[1] position/orientation/trajectory is coming from other sensors with their own error bars, namely your IMU and whatever information the ground can glean from radio signals.
If your LPS accuracy is better than your IMU accuracy, I don't see why it wouldn't make sense to start using it once it's available.
[1] gotta call it something and GPS doesn't really fit
My case was about not having radar at all. Having GPS could buy you some time and start braking already based on GPS even if the radar is still out. Yes, might burn some additional fuel but burning too late sucks harder I suppose.
Also: even tough I couldn't find anything about the navigation (or rather localization?) accuracy of the Moonlight system, I'd expect it to be better than 100m, but I have nothing to confirm or deny this.
Let's say you need to start the burn within a +/-10m box to come to a stop 1 to 21m above the moon surface. You want a sensor with something at least 10m precision but preferably more like 1m. That would be the radar. But then say you have something like a GPS with +/-100m precision. Does that help? Your safe window is somewhere inside that 200m but you cannot be sure where until the radar comes online. So do you use the +/-100m info from the GPS? Do you maneuver to center yourself inside its error bars? All you can be sure of is that you are somewhere within that 200m and are 95% sure you are not within the 10m window. So you make a maneuver anyway. Are you now in any better an information position? No. You are still somewhere in the 200m box and are still very likely outside the 10m box. Heck, you might have been inside the 10m box and just moved yourself out of it. You just wasted fuel. The only logical thing to do is to ignore the GPS and wait for the better/actionable information from the radar. The GPS may give you a warm fuzzy but it doesn't actually help when you only have one shot at the burn.
(This problem is mirrored in areas like missile guidance. Running parallel sensors on a missile sounds like a good idea but in reality leads to confusion, wasted energy/range and reduced chance of getting to the target.)