Yes I do accept what Haynes told me, it is just the value of that torque on even a "heavy strength" fastener does look a bit near the material's limit, okay these are "collar nuts" so there will be extra frictional forces being added/carried/taken/stolen by the extra area in contact with the lower arm, but even so it looks a bit close to taking that stud beyond its yield point which is not very safe.
I also accept that maybe these nuts having built in collars will force higher torque tightening figures, it is just that if an DIYer accidentally lubricates the area of the lower arms that the nut collars bear on, then the extra torque, over the normal level suggested for that size of fastening, will get loaded directly onto the stud itself which could over stretch it.
One final comment, in case you do not know, VW Group no longer supply replacement lower bail joint assemblies, if that ball joint fails for any reason, in the VW Group world, that lower arm will need replacing. This might be due to the possibility that releasing these nuts can cause the suspension to become miss aligned - and that would mean a full four wheel realignment, something that a VW Group workshop is trying to prevent a customer needing to pay for.
In short, maybe I should try to avoid releasing these 3 nuts on each side when replacing the springs. That probably means releasing the lower ball joint top nut - but usually access is limited!