Just because those troops are from red state America does not mean they will disobey orders to suppress secession. Do you have anything other than that to back up your statement? Something more than a guess?
Suggestion. Study the civil war especially the mobilization part. For instance, the pro Southern soldiers and officers resigned their commisions/enlistments and were allowed to peacefully repatriate to their states. They then joined the CSA/CSN. This happened thousands of times.
Would you kill people from your own state who had chosen to freely and peaceably leave a union that no longer served their interest, and in fact was doing great harm to their well being? I wouldn’t.