BG, As said - I do agree that the student should be capable of handling any emergency by the point they're taking a CPL or IR skills test.
I just can't get past the fact though that there may well be a need - let's talk about student incapacitation - for the examiner to take control. We're taught through theory that accidents and incidents rarely occur due to a single factor.....is this not a prime example where the swiss cheese holes could line up? Moreover, realistically what does the examiner NOT checking their brakes prove that's of benefit to the test?
It just seems to me that there's potential downside if it all goes Pete Tong but it proves no greater capability on behalf of the student if they're not checked.
All of which is of course caveated that I speak from perspective of having taken and passed the tests, but never having moderated one.