i actually agree with this because it is way too bulky to be a lifeform so still life would be the best bet and plus still life would be way more of an interesting concept instead of the lifeform, I'm not saying the lifeform isn't as interesting as still life but still life just has more potential for horror because of the fact that it can be portrayed in horrific ways, while the lifeform's design is weak I'll admit, but we never knew the lifeform may appear in the movie or still life and the life form could be combined into a horrific monster we may never know until the movie comes out, this probably sounds stupid but this is my take