Good Spot FFF.
I thnk that the problem is that the aerodrome markings do not accurately reflect the true situation.
The AIP is quite clear with regard to TORA, TODA and ASDA for 05.
It seems likely that if one starts at the start of 05 and measures the declared ASDA and then add on a further 30m for the "strip". From that point draw a slope of some 5% ( 1 in 20) and I expect that the "object" will be cleared.
You could do similar measurments with regard to the approach obstacle clearance surface and again I am sure that the "object" would be cleared.
Or look at it another way, the road just behind the parked aircraft could be a lot closer to the THR runway 23 without causing any limitations on the operation even if there was a line of double-decker busses parked along it!!
Thus while not ideal, there is nothing wrong per say with an object being left where you see the aircraft parked on google.
The confusion arises where the markings show that the portion of 23 prior to the threshold is fit for movement despite a) an obstacle being parked on it and b) the starter extension only being a small portion of that piece of tarmac.
This confusion is further agrivated by the fact that the AIP includes a statement that the threshold of 23 is displaced.
I think that less confusion would exist if the area prior to the starter extension for 23 was marked in accordance with CAP168 just like runway 12 and 05 are marked and appropriate taxiway markings were provided if this piece of tarmac is to be used as a taxiway.
The operator is very clear however in reminding pilots to ensure that they use the threshold for runway 23.
If aircraft are permitted to park on that piece of tarmac, what markings are in place to show the point beyond which aircraft must not park as to do so would infringe on the runway?
Getting back to your point about lining up beside the parked aircraft and starting your take-off run - two problems - 1 it is prior to the starter extension and secondly the starter extension is PPR and I would expect that the aerodrome operator would make it clear to you where you could start the take-off run from and would also take into account blast effects from your aircraft on others parked prior to the starter exctension.
As for NOTAM - not required.
Regards,
DFC