Why? I used to provide administrative support for a felony intake deputy with the DA’s office for Sacramento County in Sacramento, CA. It is the exact wording we used when we found there was insufficient evidence to prosecute.
Mainly because it deals with a high-ranking person (President). Things are so political as it is. Such wording may be legally appropriate, but it should be followed up with additional info. That sort of language can have the effect (intentional or otherwise) of undermining the President - any President.