So I called the company that manufactures Loc-Line and spoke to their sales manager.
Here's the skinny:
The 170 degree temperature guideline is for mechanical reasons. At temps higher than than the ball/socket connects becomes more prone to leakage...no big if you're using it for sparging. In fact they have FDA "Food Grade" rating to 240 degrees and she assured me there would be no possible impact to flavor, health, etc as the plastic doesn't even begin to soften until about 340 degrees.