Chances are an investor advocate relentlessly contacted TDAmeritrade and demanded they follow in Etrade's and Ameritrade's footsteps.
Don't you think TDAmeritrade are a bit professional and would base decisions upon proper DD and not from someone that would be calling them out of the blue?
Somehow I believe that TDA received information from the DTCC in regards to the ability to sell and buy shares of HRNF.