Clearly not everyone agrees, that's why it's a petition. Sign it or don't. Some riders opposing seem to believe the proponents are supporting it based on some sense of entitlement, or incorrect data about fuel consumption and pollution (although many of those arguments may be stronger if newer bikes continue to meet the stringent standards that Honda's new NC700 meets).
It's true, the lanes are designated as "High Occupancy", ostensibly to create an incentive for car pooling. A minivan or SUV with a capacity to carry 7 or more passengers is eligible for the lane with a driver and a passenger. Is that high occupancy? A motorcycle is always at 50% or 100% capacity with only the rider.
The rules have already been amended to allow "green" vehicles regardless of the number of occupants in the vehicle. Empty buses are permitted to use them because it helps in maintaining their schedules. It is not, therefore, unreasonable to grant another class of vehicle access, especially if it would be beneficial to all road users.
Motorcyclists are safer when there is less traffic around them. That doesn't mean they should be restricted to riding only in light traffic. Comments like "if you're afraid to ride on the highway in traffic, stay home or get a car" may have (very little) merit when discussing risk, but that's not the point. If there is a reasonable, affordable and available way to promote safety, it should be taken. A reduction in injuries is a benefit to everyone in Ontario, and taking reasonable steps to promote that safety - especially when it is at NO COST to anyone else, makes sense. A shoulder on one side of the lane and a buffer zone with limited access on the other is a reasonable step to promote safety. It's not the only reason I support it, but it's one of the most important to me.
It's not about entitlement or privilege. It's about safety and common sense.