Rule of thumb: Players who are diehard rolling enthusiasts make their own "luck" through multiple rerolls, be it mulliganing on their current set or outright disregarding low dice. When you're able to discard the results of your bad luck, there's no risk to rollers.
I don't think Tukka's players are intentionally trying to game the system, so much as they're enjoying the results of the times they rolled well. Still, it's worth it to bring the subject up before game next time, and put it to a vote whether players want everybody to use point-buy or everybody to roll. It shouldn't be too hard for either side to adjust their character's stats to the appropriate method.