because throwing a tablespoon of catsup (or ketchup) away in an almost empty bottle is such a crime and a waste
Some people (like me) whose parents grew up during wartime or similar were brought up to think exactly that. A bit of water in the bottle, shake it up and throw it in when making pasta sauce or similar calms that irrational food wasting guilt by getting the last bit out of a normal bottle.
I think the article is an example of a journalist saying "how can we use this in the home" when asking about a new scientific advance. Applied uses may end up really being something in minerals processing but it's harder for most to relate to that than kitchen stuff.