Lew, what you describes makes sense but you must take directionality into consideration.
First off, we are describing a hypothetical tonearm, it must be straight, the cartridge must be in line with its axis and it must not have an overhang. As you stated if it has an overhang it will never have a null point. But let us assume that it has a null point at the groove which is tangent with the tone arm pivot point. At this one point there will be no skating force. Now take a standard arm at its null point, due to the offset angle it will have a skating force.
Now as this 0 offset arm travels away from the null point, in the spindle direction then the skating force should be pushing the arm in wards, however moving out wards towards the record's edge the skating force should be pushing the stylus out wards. So I agree, that there is a force, but it is not the same as the skating force caused by the offset angle and I would guess that it is much smaller in magnitude.
First off, we are describing a hypothetical tonearm, it must be straight, the cartridge must be in line with its axis and it must not have an overhang. As you stated if it has an overhang it will never have a null point. But let us assume that it has a null point at the groove which is tangent with the tone arm pivot point. At this one point there will be no skating force. Now take a standard arm at its null point, due to the offset angle it will have a skating force.
Now as this 0 offset arm travels away from the null point, in the spindle direction then the skating force should be pushing the arm in wards, however moving out wards towards the record's edge the skating force should be pushing the stylus out wards. So I agree, that there is a force, but it is not the same as the skating force caused by the offset angle and I would guess that it is much smaller in magnitude.