Earlier quoted context omitted.
No, it looks like people can be scared by correlation. Of course changes in diet can be dangerous (you just try switching to an all cyanide diet). But "liquid protein products"? Like milk? Or protein shakes? There are certainly plenty of "liquid protein products" on the market, and heavily used, and tons more protein products sold as powders to be mixed with water, milk or juice by consumers. Somehow we don't have we…
Milk cannot not be liquid protein product by almost any sane definition. It has more fat and more carbohydrates per gram than protein.
It is far easier to stomach large amounts of protein (due to taste and consistency) when mixed with a lot of carbs than alone, and unless you're cutting you generally need a lot of carbs too when training hard, so there's little incentive for most general protein supplements to keep carbs down.
In fact, there are a large number of protein supplements on the market where the majority of calories comes from carbs and fat, and many will have more carbs alone by weight than protein (many often also are specifically advertised for weight gain / bulking).
They are still commonly referred to as protein products because the main basis for calling something a protein supplement amongst suppliers and people using them is generally large amounts of protein, not low amounts of carbs and fats. (And yes, that means some of them - intentionally - have massive amounts of calories)
You also probably talk about "pure" milk, but there's also a number of milk products on the market that are milk + extra casein extracted from milk, for very high protein concentrations - my favourite has about 40g of protein per 300ml; you are free to not accept that as "milk", but it tastes like milk and is generally marketed as "protein milk" or similar.
But milk alone is also frequently used by weight lifters for the decent protein content and good ration of protein, carbs and fat (a well known "supplemental diet" for bulking for lifters is called GOMAD: Gallon Of Milk A Day)
The main point being that large amounts of protein is being ingested in liquid form every day all around the world, and has been for decades, and we're not seeing mass deaths.
Barring actual evidence to the contrary, there's very little reason to believe that the deaths referenced in the article had anything to do with getting "liquid protein", and very good reasons to believe it was hysteria.