R62, that was actually in the original 1950s movie. It’s a guy and his girlfriend, they seek shelter in an abandoned, wrecked farmhouse, and an alien gets inside and finds them. A lot of details are similar. A version of that is in the original book I believe. It’s basically the same scene reworked except for Ogilvy, who is an original character. Here’s a clip of part of the scene.
I think the point of the Ogilivy scene is to show Ray was willing to kill to save his child. Later, he was willing to attract the attention of the alien ship that had his daughter, because he wanted to get on board where she was. At that point I think he was so tired and hysterical, he just wasn’t thinking of anything but getting her back before they killed her. Or being with her at the end. I think they were running those people through a wood chipper (or the equivalent) and then using them for fertilizer for their alien plants.
That’s why the plants were red, they were fed with blood and plants will take on the color of the water you feed them with. That’s how they make the burgundy sunflowers with burgundy stems that you buy at florists. They put dye in the water. Roses are fertilized in part with bone meal, for the calcium and other minerals. It makes them bloom. So grinding up people and using them for fertilizer to make their alien plants bloom and reproduce quickly makes sense.
The whole running theme of the movie is, Ray was an immature man when he was married and rubbed everyone the wrong way, so his wife divorced him. He had a pretty distant relationship with his kids and didn’t really know them. They kept showing Rachel relying on her brother, Robbie, not her father, for comfort. And Robbie was protective of her and obviously had spent a lot of years being the one to protect her. They felt they were fatherless. Then this emergency comes along and Ray bonds with them in a hurry. Robbie, who is older and more embittered, doesn’t trust him, until the scene where Ray lets him go. Ray realizes he doesn’t have a right to keep Robbie there because he hasn’t been a father to him. Robbie owes him nothing. Ray missed raising him through his childhood and can’t get it back.
Robbie probably told his mom and grandparents what they went through together before they parted ways, which was a lot and it probably surprised them how much Ray was willing to do for the kids. Robbie probably heard what the other adults thought about it and realized his dad had done a lot for them. And the Army wouldn’t take Robbie, so there was nothing for him to do but go to the grandparents. At his age, he could make much better time than Ray could, saddled with a kid and on foot. Maybe the Army gave him a ride.
Tim Robbins did a good job of playing Ogilvy as written. The character was too unlikable and annoying. Ogilvy just seemed like a child molester that wanted to get rid of Ray so he could rape his daughter. Too many issues to unpack with no time to do it.
Spielberg was trying to make it “okay” to kill him, by portraying him as a drunken degenerate. He overdid it and wasted screen time. They could have used that time at the end to show what Robbie, the grandparents and ex now thought of Ray’s sacrifices for the kids. No time.
They could have done every scene in the house the same without Ogilvy, and it would have worked. In the 1950s movie, the woman that panicked when confronted with the Martian was a likable character, not just a liability. Not some pervert that needed to die.