I hope Zwift adds a SmartTrainer only Race. No other types allowed. This would filter out most cheaters as they usually ride zpower or Power Meters that are calibrated wrongly. Taking part in a race without HR should not be possible. Updating your weight drastically before a race or having a Rollercoaster weight profile should get you banned from competition immediately for a certain amount of time. Changing your height should not be possible or get you banned 1 month for every inch/cm changed. People with an unrealistic Height/Weight Ratio that perform like a superhero should be banned for life.
Smart trainers can also have calibration issues. Without knowing a persons HR zones a HRM just tells you they are alive and putting out some effort.
Also, I agree somewhat with the limiting of changing weight.
A point system would be a better solution.