Would an E9 comply if ordered to attention by an O1?

Not a chance! A great time for some professional development from E9 to O1.

So would people still have the same responses if the 2LT was a direct commission and the troop was an E-6 or higher priority to commissioning?

Yes, but i dont think the O1 will like the out come. I seen a CO yell at a junior officer for not learning or listening to a senior enlisted.

I think that the O1 would benefit and learn from the E9 better if he or she would not try to throw their rank around.

Absolutely, and later on screw with him or her forever.

Mamudiya, Iraq Nov '04. Kicking back with the CSM and another SM smoking Cuban cigars in front of the CSM's hooch. They were taking turns thundering at soldiers for various sins and infractions (real and imagined) as they walked by. The porta johns were about 30 meters away and an O-3 energes from one. He casually flops his kevlar on his head,slings his M-4 over one shoulder and his flac over the other and starts to shuffle away. Without a word, the CSM takes a quarter outta his pocket and flips it and the SM calls "tails". The CSM says "You're up Ricky" The SM roars "HEY FUCK STICK!!!Get your goddamned flac on and buckle that chinstrap!!!" Capt. Fuckstick about pissed his shorts and complied immediately and scurried off to his hooch. The SM puffed on his Cuban a couple of times, chuckled and said "Life is good"

In front of troops, sure, but I'm sure things would be handled behind closed doors with superior offcers handling the verbage....

Yes, If the reason was inappropriate, the E-9 would have a "heart to heart" behind closed doors. I've had 01's call out attention when the Brigade Commander enters the room.

NO, 2lt will be straightened up or get put in place by an e9

Yes but I wouldn't want to be the butter bar that tried it