No matter what your nationality if you have gang affiliated tattoos you are bared from enlistment into any branch of the service. Each branch has slightly different rules on tattoos, however racist and gang related are bared from all services. There are over 2 million people in the military.
You forgot to look at all the other gangs that are in the military as well. There are some members of predominantly African American gangs, there are biker gangs and white supremacist groups. There are over 2 million people in the military. You get people from all walks of life with all sorts of questionable morals and previous affiliations. Some were in gangs or affiliated with gangs through family members before they enlisted.
Also in order to enlist you have to pass the ASVAB. It requires the ability read and comprehend English at a moderate level. Having been a recruiter in the Marine Corps and the Army National Guard I can tell you that most people of questionable country's of birth who want to join the military usually can not score high enough on the screening test given in the recruiters office. The ones who can usually have one or more other disqualifying factors. The United States military is one of the most selective employers in the world. Most medical issues disqualify you from enlistment.
I personally like the fact that military service will be incorporated into a pathway to citizenship.
1, thank you for your service
2, I don't like any pathway to citizenship as it rewards lawbreakers and many of these people have proven their loyalty lies with countries their parents broke into ours from ( Mexican flags at protests anyone) or their race instead of the usa.
2a If there is going to be a pathway to citizenship that I am against 100% I will admit I too like the idea military service is a part
On the mention of the asvab and so forth they are great points. The problem is the lawlessness the current admin operates that could be waived as well as the president magically did executive amnesty and plans to do more. I don't think it would be legal, but would not put it past him doing it.