This is so ridiculous. What's the use of a turbine rating for a PPL pilot or even a low time CPL pilot? Nobody is going to hire you at 135 or even 185 hours and let you fly his turbine helicopter.
The only reason why your instructor told you to do so is, that either he himself needs turbine time or cause he wants to make some extra money by selling you the more expensive turbine hours.

Get some experience on pistons first and soon or later you'll find a company that is willing to spend some time and money and pay for your turbine rating.