No its not true.. Premium processing will just get you your results sooner which is more or less 15 days. If you get RFE then the clock will stop on your Premium Processing until you provide them with the information and documentation that they need.
I filed on Premium processing and got RFE in 5 days but since I got an RFE, the clock stopped and restarted a day after they received the information. The decision was approved within 12 days total(not counting the days in between where they asked for more documentation). Hope this helps