Your question is not really seeking any legal advice, but as a former Air Force JAG defense counsel, I will be happy to decode for you what this means.
The reference to "CRUITMAN-ENL, Chapter 6" is the authority for removing, or rather discharging your son from the U.S. Navy’s delayed enlistment program. CRUITMAN-ENL is the acronym for the Navy’s Recruiting Manual — Enlisted version, and somewhere in Chapter 6, it states the policy for handling people in your son’s situation.
ZBA is a “discharge case code.” This is a code which lets all the service branches know in an instant what the basis was for your son’s discharge. ZBA stands for “moral disqualification” and this standardized code is used in all braches personnel systems.
A moral disqualification usually means that the person committed a criminal offense which impacts their eligibility to serve in the military. It could also mean that they are on an active parole or court supervised probation which will not allow them to enlist.
Finally, EPTS means “existed prior to service.”
An entry level separation, or an ELS for short, is usually a separation from the military for which there is no specific service characterization. The term characterization is a standardized descriptor for a military member’s service. Often times the characterization is “Honorable” but if not so, the characterization could be “General” or “under other than honorable” conditions. But when a person has less than six months on active duty, the only available separation characterization will be ELS unless the person commits a serious criminal offense and gets court-martialed or punitively discharged.
For example, if someone gets a serious medical issue at boot camp that makes them unable to complete training, they will most likely receive an ELS. But remember they must have less than 180 days, and this is why it specifies 98 days on your son’s paperwork.
Please note that an ELS is NOT technically considered to be a discharge. It’s more along the lines of letting some leave without actually kicking them out. And if someone gets an ELS, they can sometimes re-enlist into the military once the thing which got them removed gets corrected.
So to put it all together, apparently your son was an applicant for enlistment into the U.S. Navy and got in some sort of legal trouble or did something which made him ineligible to ship to boot camp. His service length was less than 180 days so he got an ELS. Depending on what it was which caused this separation, he may be able to get his record fixed or obtain a waiver and then he could potentially re-enlist.
I hope this clears up all of your questions and concerns.
Upon signing an enlistment contract, a person is considered an enlistee in the Delayed Entry Program (DEP)until he or she shows up for basic training (boot camp). The DEP allows the enlistee to delay his or her training for his or her purposes (finish schooling, get affairs in order, prepare for military service, etc.) and the purposes of the military service (e.g. manage the entry of recruits into the training program in an orderly and efficient manner). Just as there are qualifications (and disqualifications) to enlistment, there are events and conditions that cause the military to separate from service enlistees in the DEP and on active military service. In your son's case, the cited reason tells me that he had an arrest, a criminal conviction, or a confirmed incident of illegal drug usage. I am making no comment on whether such an event actually occurred, but clearly your son's military service thought that one of those events occurred. He can seek enlistment again, but he will have to either convince his prospective military service that the event did not occur, or obtain a waiver from the rule that makes that event a disqualification to military service. It can be done.