Does it actually help them along if it’s that many items? It’s hard for me to imagine that 217 instances of a 6 letter word instead of a 7 letter word is much easier to format. My view is that trial and error, obsessively rewriting sentences to fit, is much more likely.
EDIT to clarify: what I mean is that I don’t think there was a master plan where words were misspelt to make this work. I think it’s rather brute forces with a lot of obsessive time and effort. Not in a bad way of course, I really enjoy what they did.
EDIT2: especially when rocket is already a 6 letter word, and likely could be used interchangeably in the guide. I feel that turning missile into one as well wouldn’t help the goal in the slightest, would only make it more difficult.