The second point was clarified above in the thread, yes, it's not a good idea to touch down at the max descent rate (2m/s in the current firmware). Not only is it really hard on the bird (pretty much a crash), but you'd probably experience some VRS (Vortex Ring State aka descent with power aka wobble of death) close to the ground which will likely cause a worse crash. Good to ease off early enough to avoid VRS and/or a hard landing.
But the first point is not accurate. Pulling both sticks down (back) will not kill motors or cause the drone to fall out of the sky or necessarily cause a crash. True, both sticks straight down will result in the drone pitching backwards at perhaps 30 mph while descending 2m/s, which is a bit sketchy but if the drone is 500 ft up it could be a maneuver that works for a bit.
However it's not CSC (Combination Stick Command), which has both sticks not just down but either both inward or both outward (and I think the pattern has to match the way it was started for that flight?). Now granted pulling both sticks down is that much closer to the CSC pattern, but it would still require a bit of effort to pull both inward or outward as well. Personally I've never done an accidental CSC in all the hours I've flown my Phantom 3A, even though I've done some "interesting" and at times hectic maneuvers with the sticks all over the place.
Sorry, not trying to be nitpicky, just wanted to make sure we're being clear.