what you say is not true. This game is not for young children. You talk as if 5-year-olds were going to play it. It is a game for teenagers in any case but not for babies. Today's children are used to throwing grenades and seeing horrible things in gta games etc. I don't think they will be scared by seeing a dinosaur eat a small person. it will be a licensing issue
All of that is irrelevant.
Children today are some of the most foul-mouthed and corrupt individuals on the planet. They are far more aware than the blissful ignorance their parents and society might want to believe them to be, but that disconnect is where this idea stems from. Big corporations like Universal with a worldwide audience for their IP want to maximize profits by making their films as broad appealing as possible. This often comes at the expense of creative liberty and certain subjects become taboo or too controversial to entertain even if its spin-off or licensed materials like JWE2.
China is a huge marketplace for Hollywood films and the gaming industry, and the CCP have insane censorship policies that must be enforced if a title is to release there. This marketplace is lucrative, so more often than not we see studios taking preemptive action to censor, or avoid subjects that might not do well there. They also don't like having to make different cuts of films for different markets as all that editing costs money they don't want to spend. This is just the reality of the world, things offensive to some groups or in some cultures has an impact on IP that caters to a global marketplace.
We also have to consider that not every child in the world is the same. Some kids are naturally more sensitive, the environment they were raised in, how they were cared for, the culture, etc. all these things have an impact on how kids develop. Kids in the West who are pretty desensitized aren't reflective of all kids in their respective countries much less others around the world. You could really argue blood and gore in general is not a healthy thing, anyway, this could go in circles forever and we are getting into territory very quickly where this thread could be locked.
I don't like it or necessarily agree with every decision companies like Universal or Frontier make, but it is what it is and at least its still a quality product. I wouldn't doubt that a modder might figure out how to add child guests some time either if you really want to get around it.