I have no idea where the explicit 'max arm length rule' went, but the 1.5 * Htop for an extended robot should be even a little bit more relaxed and leave room for some improvements.
The previously defined maximum 'wingspan' of 1.2 * Htop would leave a maximum arm length of 0.6 * Htop (assuming a zero width of the robot).
If the robot may extend to 1.5 * Htop, we have a head of 0.05 ... 0.25 * Htop (which starts at the shoulder) to be added to 0.5 * Htop. Thus the smallest maximum arm length (for a head of 0.05* Htop) would be 0.55 * Htop, whilst the largest maximum would be 0.75 * Htop (for the largest possible head).
(If I remember correctly, the typical human arm length, including hand, is somewhere around 0.45 * Htop.)
((Maybe for the future we should define that the robots have to stay within some percentile of real human dimensions.))