I cannot find an official ruling on this, nor can I find a Power Spray or Power Cancel ruling that would offer some clues here, so here are my thoughts. I believe the effect of discarding the {R} energy would be an effect of the POWER that this card would negate. The wording on Ninetale's Poké-POWER is different from the mandatory conditional card texts like Electivire FB LV. X's "Energy Recycle", which states that if you use that POWER, your turn ends.
Just my thoughts, though. What do the other professors think?