I predict that it mostly gets worked around, by using only a few extra words.
“The sky is something other than blue” and “I will be somewhere else tomorrow” are both semantically-equivalent to the forbidden forms. Even “I deny that the sky is blue” is a positive-form negation of the object-level statement.
I suspect all such workarounds depend on one of a relatively small set of negation-enabling words, such as “other”, “else”, and “deny”, as you demonstrate. Prohibiting more words should eventually block all workarounds, while making writing more annoying.
I suspect all such workarounds depend on one of a relatively small set of negation-enabling words, such as “other”, “else”, and “deny”, as you demonstrate. Prohibiting more words should eventually block all workarounds, while making writing more annoying.