This example is no justification for logging and retaining the information.
It's only a justification for using it real time as it occurs, and with the callers permission.
For many years this has happened with mobile calls to the emergency services. Last time I rang 999 from my mobile I spoke initially to an emergency operator on the mobile network, then I heard them hand me over to the "real" emergency operator and give my number and approximate position before dropping out of the call and connecting me through. So that when I said the name of the road I was reporting the incident in, the operator didn't need to know the postcode or town name (which if you were a bit lost in strange parts you may not actually know reliably) as they were already on the correct page of the map thanks to the location info the mobile operator had passed over.
I thought it was rather cool use of technology at the time and didn't feel at all intruded upon or spied on. Although why they couldn't send that information in digital data form instead of spoken words is a little more concern to those of us familiar with Heath Robinson!
I'm sure that any day now the "think about the children" line will be thrown in, saying that missing children could be traced by this system (because everyone is a paedo, rapist or murdered these days don't-you-know). Which of course will be instantly defeated by the villain in question when he checks his victim for a mobile phone (which I'm sure they would do anyway) and throws it out of the car window.
How about we set up a test study group... Like say all the MPs. Then we will study the movement log information and decide if it is of any use... Who knows, it might detect fraud, dubious meetings, or where they go instead of attending parliament and representing the views of the people. That is their job isn't it?