I-Ford - I think there were other issues in at least one of the GOA 'incidents' and in view of the amount of metal 'under your feet' on finals there I would be very reluctant to 'land short' on that runway!
IMO if you cannot guarantee stopping in the available runway length - do something else - dire emergencies excluded, of course. The reference you link to clearly says it is the pilot's responsibilty to maintain safety - which is ALWAYS the case, and I can see NO reason to land 'short' in normal ops. I would suggest that the question 'is it legal' is less relevant than 'is it sensible'?
If, OTH, your aircraft can fly, say, a 5 or 6 degree slope, then perhaps you can apply for an alleviation, but equally the types that can do that should not need more than 2100mtrs?
As to whether it is 'legal', I would suggest that you would not encounter a problem from the airport authorities providing the surface is 'suitable', but as is the case of R29 at GOA your operating company may wish you to explain a significant 'below gp' event or a high rate of descent at a late stage - or even worse, a piece of dockyard crane in your undercarriage.
