He can request a guaranteed district, though only certain districts can be guaranteed. Only a recruiter would know which ones, if any, are currently being offiered under the guarantee program. I'm not sure if specific units can be guaranteed.
Regardless, make sure to read the fine print and all reference materials provided. I believe the member is restricted from requesting "A" school for a specific period of time in exchange for the guarantee. Also, there may be a minimum enlistment obligation (6 yrs?) necessary to execute a guarantee.
Historically, Coast Guard guarantees come with enough strings attached to knit a sweater. Example of a BIG string (more like rope):
Person asks for and receives guaranteed district assignment. In this case we'll say District 1 (Boston) and is assigned to Station Gloucester. Now, let's say the restriction is 1 year before this person can apply for any "A" school. That seems okay on the surface but puts the person at a disadvantage if a desired school has a long wait list. The sooner a name can be put on the list the better. What may have been a 12 month wait for school just jumped to 18 months to 2 years.
I can't say it enough - read and understand all the caveats to guaranteed district.