In the UK ATC manual there is an instruction which says 'an aircraft shall be instructed to carry out a missed approach when it appears to be dangerously positioned on final approach'.
This is then expanded by an entry which states that 'dangerously positioned' is difficult to define and basically leaves it to the professional judgement of the controller looking at the aircraft, either on RADAR or out the window.
In my opinion this does give us the power to tell them to throw it away if we don't like the look of it. I would certainly defend anyone who did so and was then questioned about it. Conversely, I wouldn't expect it to be a decision that the controller made lightly due to the issues involved in late go-arounds from a low height.
Whether someone is already cleared to land or not is irrelevant. Would a pilot ignore a go-around instruction due to a runway infringement just because they'd already got landing clearance?
YM