This is exactly what a trademark is intended for. If I started a home goods store called "Home Hut", and made the logo a large orange square... i'd also be infringing, and for good reason. Home depot has built a reputation, and that trade mark orange is representative of that reputation.
And if I start a home improvement store using a tomatoish orange and call it "Bob's Home Store" would that also fall afoul of trademark in your book?
In the case of the DMM in question, it's not direct knock-off of a Fluke and according to SF the color is more of an orange-yellow than the Fluke safety yellow. SF's whole point is that the TM terms are too vague. Gray with a yellow border. What shade of gray? What shade of yellow? I don't get to claim a whole primary color and say you can make a DMM using any color even close to this.
