I don't agree. It was a fun family attraction for my family. My kids knew they were at Disney filled with fantasy and the could differentiate. They were bright, they knew to close their eyes in any movie, TV Show or attraction the was visually scary. The movement part of Alien wasn't a rough ride. It had a 48" height, so about 8 years old. My kids by age 8 were seasoned Disney guests.
My DS rode Body Wars at age 3 when it opened. It only had an age requirement, which was 3 years old, originally there was not a height requirement. He came off laughing, me and DH a bit nauseous. When it came time for my DD as a preschooler to ride Twilight we explained the actual ride as only a elevator that goes down fast, no bumping or turning upside down. My toddlers Boo'd the ghoasts in HM, shot the pirates with their finger guns and were bored out their minds with Small World.
My advice often to parents is don't scare your kids. Don't overly describe the attraction. Most can handle attractions. And bribes worked well for us too. With kids 5 years apart in age we were so done with baby swap.