Should active or reserve mil pers be discharged "other than honorable" for displaying or assoc with Nazi or White Supremacy symbols/groups?

Yes. Those people cost us 300,000 military personnel during WWII and should not be allowed to exist. The home grown Hitler worshipers Aryan Nations, White Supremacists, and all others of their ilk have only one thing in mind - overthrowing Democracy. Their document are pretty clear on that. eg. Turner Diaries.

All but two of 27 service members have been formally investigated and 18 service members were disciplined or separated from the military.
https://www.marinecorpstimes.com/news/2019/09/13/27-reports-of-extremist-activity-by-us-service-members-over-the-past-5-years-dod-says/?utm_source=Sailthru&utm_medium=email&utm_campaign=EBB%2009.16.19&utm_term=Editorial%20-%20Military%20-%20Early%20Bird%20Brief

This is exactly how the Corps should respond to such cases:

In June 2018, Pistolis was sentenced before a military court to 28 days confinement, reduction in rank to E-1 and forfeiture of two-thirds pay for one month. He was booted from the Marine Corps in July 2018.
https://www.marinecorpstimes.com/news/your-marine-corps/2019/09/04/the-neo-nazi-boot-inside-one-marines-descent-into-extremism/?utm_source=Sailthru&utm_medium=email&utm_campaign=New%20Campaign&utm_term=Editorial%20-%20Marine%20Corps%20-%20Daily%20News%20Roundup

A U.S. Army Recruiting Command leader has been suspended for allegedly using the notorious phrase ( "Arbeit Macht Frei [Work Will Set You Free]" ) that hung over the entrance to a World War II Nazi death camp in a memo to encourage recruiters to sign up more recruits. If an investigation reveals that this person is a member of a neo-Nazi organization, hasn't he or she dishonored the sacrifice of U.S. military personnel who fought, were wounded, and/or died in the World War II struggle against the Nazis, and shouldn't he or she be relieved of duty and discharged under "other than honorable" conditions?

https://www.military.com/daily-news/2019/08/26/army-recruiting-leader-awaits-judgment-after-using-nazi-death-camp-motto-memo.html?ESRC=eb_190827.nl

Please define where these flags are displayed?? Duty station or barracks??

Is do the command going to do the same thing with a "Black Lives Matter" display?? I can see it if the service member was a Neo-Nazi or KKK member, then the command should investigate to determine if it was a joke or a serious threat.