[Cory]

Technically the rules don't say that they can't be pink, but rather that if their robot interferes with the vision system they will be asked to rectify the situation.

After looking up the rules, the only rule I see is <R02>-C Any devices or decorations specifically intended to jam or interfere with the remote sensing
capabilities (including vision systems, acoustic range finders, sonars, infra-red proximity detectors, etc.) of another robot (i.e. changing ROBOT color to confuse opponent’s vision system).

Technically they'd never even be changing their color.

If I missed another pertinent section of the manual, someone please correct me.