Am 26.02.2019 um 10:35 schrieb De'vID:> 
> The sentence used to introduce this restriction in TKD is: {yaS qIppu'
> 'e' vIlegh}.
>
> This sentence didn't appear in Star Trek III, but was something with
> this grammar actually spoken in the movie which forced Okrand to make
> this restriction?

Yes: {qama'pu' jonta' neH}

In the first version, it was meant to say "I told you: only the engine".
The new subtitles of the movie changed to "I wanted to take prisoners".
Okrand had to backfit the sentence structure, but the suffix {-ta'} was
on the first verb instead of the second one. So, the rule was set: the
second verb does not take the aspect suffix.

NB: this is not confirmed, but I think it's obvious.