He means that we just have to trust that Tom will use the Preferred Shares properly and not dilute the crap out of this stock! Those shares have the potential to convert into 80% of whatever the o/s is at the time which can completely ruin the share structure. IMO, I trust Tom and his reputation that he won't do this but there's always the possibility unfortunately.
Basically if any entity tryed to takeover Tom S company, he could create major dilution of he's company, so the value would not be atractive to a financial takeover.