Well, I'm so glad you "generally" support the military since you know nothing of it. You have absolutely no idea of what you are talking about regarding the incident.
Ok, you explain it to me. Again, if this is not being misreported, the cop sees some young toughs in a pickup, stops them because one is riding in the back in a 40 degree drizzle, and is attacked by the occupants of the truck. Are the three in uniform? No. Are they marked in any way to show that they are taking part in an exersize? No. Can the cop be expected to be clarivoient? No.
The spec op guys fell to their own bad judgment and the bad judgement of their superiors.
Running this kind of drill without tight controls will inevitably cause problems. This time, it got people killed.