Hramblings: Cheap food, secondary usage and the great awakening
At the risk of giving aid and comfort to the enemy, this test is entertaining, but has some problems. First, you can't be absolutely certain that the pink slime burger had any pink slime in it. More importantly, it wasn't a blind taste test. You knew which burger was the unadulterated one. Your comments on texture and flavor profile could have been affected by confirmation bias. But as you say, not enough to keep you from eating both burgers.
As for food handling, cooking a burger to medium rare that you didn't grind yourself is not a great idea whether it has pink slime in it or not.
The hearts of the foodies among us beat fast when they hear talk of nose to tail cooking, but get tense when they realize what that means. Carcasses are broken down into primals which are cut into steaks and chops. Pretty much everything else goes into ground meat and sausages. These things are done to minimize waste and maximize yield.
In short, safe to eat in terms of pathogens is a separate question from nutrition, palatability, target market, and a rising discomfort with the mechanics of our retail food webs. My vegan friends have made their peace with the last issue already. I'm in the "everything is better with bacon" faction.
Food is the US is generally cheap. Food is cheaper than its ever been. To meet that price point, we make a whole series of compromises. As a culture, we need to decide to pay more to get more. Pink slime is the tip of the iceberg.