There's not a single source supporting the "massive" shorting assertion. They are all just regurgitating the Short Interest Report in some form or another. These web sites have all downloaded the report from FINRA. FINRA is THE source and they tell you in plain language the report cannot be used the way everyone is trying to use it.
You can't short a penny stock. You don't want to short a penny stock. The upside is limited and the downside is infinite. No one is going to take that bet. No one.