Really ANYTHING that digests too fast is more likely to be stored as fat than something that digests slowly. We often think of this only in terms of insulin and carbohydrates, but it applies to protein also. There is limited caloric storage in the body, except when it comes to fat storage, which is unlimited.
If you consume 90g of protein in red meat, it isn't going to digest very quickly, probably over 2+ hours (likely great individual variance). So it is more likely to be either a) used for protein synthesis, or b) metabolized into energy and burned or stored as glycogen. When you eat 90g of protein from whey, it is going to digest very quickly. Some will be used for protein synthesis, but excess must be turned into carbohydrate because there is no storage system in the body for protein. At this point it works like any other carb, excess that is not stored in liver or muscle glycogen is converted into fat.
Don't over complicate this concept, this is basic nutrition.
As I've noticed with some other threads, a lot of people have some very strong opinions about protein and fat storage. These opinions are often not based in science. They draw these conclusions because they don't look at the big picture - they can't see the forest through the trees.
Here is an theoretical example. Say over 3 hours you burn 300 calories. Let's also assume glycogen storage is full. If you eat a 300 calorie meal that digests evenly over 3 hours, you will not store any of it as fat. If you eat a 300 calorie meal that digest over 1 hour, you will store 200 calories of it as fat.
These concepts are not only theoretical, but also practical, and you can see them clearly in results when dieting.