While Sessions does mention some names initially, his latter paragraphs utilize titles as he is sort of outlining the duties. He used the term Inspector General several times before using the words DAG.
Altogether, there was around 7 Inspector General, 3 Attorney General, 2 DAG, and Senior Federal Prosecutor. Given that the term DAG was within those paragraphs, I would not assign very much importance to the term as being indicative of any future action with respect to RR. JMHO
Sessions also referred to Horowitz by name, in conjunction with this set of investigations.
The second half of p2 and first half of p3 are clinical descriptions of "the system," so use of titles there is natural.
And in closing, Sessions exhorts his recipients to contact him (Sessions) directly.
Rosenstein is not mentioned by name, at all.