You're right -- the Sgt. Maj. probably wouldn't do anything. But you can believe the NCO's would....
I had a somewhat similar situation in my unit once with a white Marine putting up racist stuff in his NCO room. Some of the black NCO's complained, the kid was told to take it down, but wouldn't because he claimed a "free speech" right.
Anyway, he came to see me (the XO) one day because he'd apparently been threatened by some other Marines that he'd get the crap beaten out of him if he didn't take it down. He told me the whole story, and asked that we protect him. I told him I didn't see the need for any protection, but that he ought to be really careful walking down the steps from the barracks because he might slip and get badly hurt.
His jaw dropped, and he then went in to talk to the CO. He ratted me out as basically endorsing him getting pummelled. The CO listened, then told him that he agreed with me that the stairs were slippery and that he should be careful. The kid got the message, and that stuff came down.
We don't tolerate that stuff in the Corps, and there are plenty of extra-judicial ways of handling it. A good ass-kicking may be a nice start.
The Marines will be good for him. He sounds like he's has youthful errr...ignorance. Marines will turn him into a real man. Plus he'll meet different kinds of black people and I assume that the whole race thing falls away pretty quickly during the three months at Parris Island.
In other words, he wanted you to help him destroy unit cohesion by championing his personal idiosyncracies - idiosyncracies that he was unable to defend by himself?
Did he join the USMC to be babysat?
It's hard to see in the dark...
I can't hold you being an ex-marine against you. ;-)
I thought, though, once a Marine, always a Marine. What happened to "...the halls of Montezuma...."
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there is also UCMJ to take care of the real trouble-makers. I believe it's article 134 (the catch-all)!!