Who was the old man?

[The Might]

Whilst constantly trying to prove me wrong, I don't see a lot of proof for you being right.

Ok, so I admit the idea with the wraith was a bit stupid, but can you provide me with proof that Saruman had a good reason to run along, say "boo!" to the horses and run along again without using his voice on the travellers or questioning them.

He needed to know what had happened to the Ring, it was a question that was on his mind as seen in some of the quotes above, so why would he not try to find out something from these three guys, they were after all suspiciously close to the place the Orcs were defeated.

Your idea mentioned earlier was that...

having recently commanded his orcs to cut trees from Fangorn, he knows that he's behind enemy lines and so cannot spend too much time on what appears a worthless interrogation

I am sure Saruman had no idea the Ents would have revolted, you see that clearly in the book.

'When the Ents had reduced a large part of the southern walls to rubbish, and what was left of his people had bolted and deserted him, Saruman fled in a panic. He seems to have been at the gates when we arrived: I expect he came to watch his splendid army march out. When the Ents broke their way in, he left in a hurry.

So I doubt Saruman felt to be behind enemy lines due to the Ents and considering how much he wanted the Ring it would only be logical for him to try and find out more about what had happened; as we see above he had no idea whether the Orcs were carrying any prisoners, he could have asked them that.