The CSM review for this game is quite lacking, it appears to be written by a parent with little knowledge of the game who simply watched their kid play for a bit. Having a lot more first-hand experience with the game, I will try to write a replacement review.
POSITIVE MESSAGES: 3/5
The game centers around a race called the Tenno, who have been mostly wiped out by a clone army called the Grineer. During your journey as a Tenno, you will constantly be killing enemies like the Grineer, greedy unethical scientists called the Corpus, and characters infected with a zombie-like virus called Infestation. There is very little moral ambiguity, and there are a lot of messages about honor and mercy. (Although there is a lot of killing)
POSITIVE ROLE MODELS: 2/5
You don't really know much about your character, (which allows you to project your own personality onto them), but you know a lot about the supporting characters: Lotus, a charismatic leader who guides you on your journey and helps you from a distance, and Ordis, a glitchy (on purpose) robot butler-like character in your spaceship who is extremely loyal and helpful.
EASE OF PLAY: 1/5
This is one of the categories in which I disagree with the original review greatly. While the controls are very intuitive and explained well, the rest of the game is not. You kind of get thrown into this universe, and while you can move and shoot easily enough, it will be very hard to progress and learn about the game unless you use the Warframe Wiki, a third-party website with all the knowledge of the game you will ever need and more.
This is where I know the writer of the review was misinformed. The game is rated M for a reason, enemies will get sliced in half, heads will get blown/sliced off, enemies get dismembered, and arrows can stick enemies to walls. A lot of blood and gore is visible, and it can be somewhat overwhelming. BUT... you can turn it all off. In the menu, options/gameplay settings, there is a well-visible option to turn gore off, which will get rid of BASICALLY EVERYTHING I MENTIONED ABOVE. There still is a small red splash when you hit an enemy, but it is much less graphic. This really comes down to whether or not you trust your child to keep the gore turned off. Without gore on, it is basically a T-rated game, but with it, it is definitely M. I am not allowed to play games like Call of Duty or Grand Theft Auto, but my parents trust me to keep gore off in this game.
SEX AND NUDITY: 1/5
This is an easy category to review. All you see of your character is a suit of armor (called a "warframe"). Some of the armors are male forms, some are female. The female armors are a bit "form fitting," with somewhat sexual figures, but they are just armors, and there is no skin or nudity whatsoever.
Warframe is a "free-to-play" game with an excellent pricing structure, and there are in-game purchases that can cost a lot of money. Everything in the game is obtainable for free, but some of it takes hours and hours to obtain. You can buy these harder to get items with platinum, a secondary currency that can be purchased for real money. Every once and a while, the game awards coupons for 20-75% off a platinum purchase, which might entice someone to buy platinum. I myself have spent $25 on the game (when I got a 75% off coupon), but I have no plans to spend any more money, because I have all the platinum I need. As long as your child is financially responsible, and/or doesn't have complete uncontrolled access to a credit card or PayPal account, there should be no problem here.
Warframe is partially a multiplayer game, and while you can play it solo if you want to, it is much more effective to play in a group. I think this is a good thing, as it teaches teamwork and everyone is on the same side, reducing the chance that anyone will get angry. There is some swearing, but nothing abusive like you would find in most Player-vs-Player games and you can ignore the chat windows if you want to.
DRINKING, DRUGS, AND SMOKING: 0/5
I have not come across ANY drinking/drug references in my time playing the game.
I highly recommend this game. I have been playing it for a few months and still haven't gotten tired of it. Be warned though, there are parts of the game that require a lot of time spent, so it is important to manage your time. When I first started, I got somewhat addicted, playing multiple hours a day, but I have gotten it under control now and I have an absolute blast playing Warframe with my friends.
The game also has one of the nicest communities I have EVER seen. I think that because it is a CO-OP game, people are not at odds with each other, and don't complain about certain warframes being "overpowered" or unfair. (Probably because everybody is overpowered, which I think is really fun.) It teaches teamwork and cooperation through the co-op missions, so as long as your child is responsible with their time and money, they should have no problem having tons of fun in Warframe!