Buddy who told you that you can't short penny stocks. All brokers allow you to short penny stocks, some brokers dont allow you to trade period OTC or Penny sheets. But if they allow you to trade it then you can short it.
There is a guy called Tim Sykes that has a website all about shorting penny stocks. This goes to show that the information you present about TECO is wrong, and the statements you make about trading even more wrong.
Um then why is there a short interest reported? Also to correct you, to pump a stock there needs to be a volume of shares owned pushed into a stock to make it rise then those owned shares are dumped when the pps is moved higher. A short is borrowing shares to sell at a higher price thinking the stock will move lower then buys at the lower price to return the borrowed shares. These are the facts please call your broker!