I suspect we'll see some clarifying data from either Office of the Secretary of Dept of the Army today.
You come to the US on a work Visa from Brazil. You decided to serve. You work with a recruiter, fill out the forms, take the PT test and the oath. But while you wait to ship out to basic, investigators learn you were once a runner for a Rio drug cartel.
1. Immigrants are still welcome to earn citizenship through service.
2. DoD is not conducting widespread expulsion of non-citizens.
3. Participation in this program is down, but may be do to external factors like strong economy or stricter federal immigration law.
4. I am not sure if the 2017 memo instituted a tougher crackdown on non-citizen applicants, or was a departure from prior policy. I do know the MAVNI program came under scrutiny for just that, and had to relax standards after good reporting from Stars & Stripes.