I looked at a bunch of vehicles a few weeks ago before we bought a Honda Odyssey. Looked at several SUVs, none in that class, but I'm betting the second row seats work about the same. When you fold the seats down to make a flat surface for cargo in an SUV, they don't "lock" down. They just fold. The seat back can still pop up, pretty easily if you are strong enough to move it. Generally, the bottom of the seat lifts up from the back and forward (it may lock) and then the back of the seat folds down and doesn't lock. It wouldn't be easy either for a kiddo to climb up into the SUV and over that seat either.
But most of the second row seats slide forward to allow third row access and it's not that difficult. For my kids, I decided it's too difficult for them. They are only 8 & 5, and our oldest has some special needs. But again, I was looking at the Honda Pilot, Nissan Pathfinder, etc. Not Infiniti, Lexus, etc. Their seats may adjust a bit differently. The Honda Pilots second row seats folded and slid forward easily though to allow third row access. I think my son could have done it and gotten better at it with practice. I just didn't want to deal with it day in and day out.
If the seat folds the way I'm picturing it, I personally would not be comfortable with my kids climbing over that folded seat every day or the chance of it popping up in a wreck. If it folds flat into the floor, like the stow and go seats of some minivans, I'd be fine with it. It's not going to magically flip up and go past it's latching point without extra weight on it, but I wouldn't want to see the forward motion of the third row child headed into it as it flipped up (*if* it would do that).