You must adjust all suspensions for AC to correct the anti-forces due to the buggy suspension forces in the public branch. Not to mention such a wide arm geometry will most likely mess up the steering geometry if you modify it for a longer lower control arm for example, and will produce an incorrect steering feel in the context of the simulation. It'll only work for this one specific use, but if you were to change the parameters at all, it will fall apart and need a redesign, is what I'd guess. If we had suspension stresses and bushings that moved, it'd be more apparent.Do you mean the front lower arm of the rear suspension?
In any case, you can say it is an oversight, since I wholly trusted Suspension Analyzer on this (camber gains, caster gains and all). I haven't checked any telemetry in the game, but it drives beatifully, so I have assumed it works as intented. Feel free to analyze it better.