Although the US army does have an "open door" policy permitting troops to take their concerns up the chain of command, they are required to proceed up the chain of command until the issue is closed. This guy bypassed about a dozen levels in the chain.
I think what we actually learned is that the troops didn't understand well enough how the move was going to be made. Apparently they thought they were going to convoy north in unarmored vehicles.
That depends on the circumstances.
Aboard my ship, we had "Captain's Call" where the lowliest "deck ape" could, in front of the assembled ship's crew, ask and/or gripe directly to the CO about whatever problem was on his mind skipping his Petty Officer, his Chief, his Division Officer, his Department Head and the XO.
One question I remember was why the CO was allowed to do such and such with his wife when the ship was in port but E-Zeros were not. He replied that when he was at the bottom of the pecking order, he could not do that either but that there was nothing stopping any junior enlisted from putting in the work required to someday command their own ship at which time they would have similar privileges.
The CO had no obligation to hold Captain's Call and put himself in positions that even had him explaining why he could do such and such with his own wife. However, the CO voluntarily put himself in that position and he accepted the consequences.
Likewise, Rumsfeld voluntarily put himself in that position.
If a superior is not willing to get smacked with tough questions that did not march up their way up the chain of command, then they should not hold such events.
If Rumsfeld really didn't want questions, he shouldn't have pretended he did. Personally, I have a higher opinion of Rumsfeld, i.e., that he's more of a straight shooter, and I have no problem with how either he or the soldier spoke.
This guy bypassed about a dozen levels in the chain.