I can't see why this limitation was set. Isn't the downside with silent shutter stronger the shorter the shutter time is? You will experience banding and rolling shotter. But my understanding is that the longer the shutter time is, the more those artefacts will be neglictable? Maybe so neglect-able that the readout from the sensor could be risen from 12 to and back to 14 bit when shutter is more than 0.5 sec?
This will be great for timelapse. Both for shutter count, and to reduce noise when shooting wild life.
You should contact Canon directly with your request. Posting a message is no more effective than posting it in social media.