I don't think he was planning on comitting suicide, he's seen later when Petit gets arrested, he's the one who let's Petit explain why shouldn't the just cut off the wires.
Not the same guy - not even the same actor - credits list the first as "Mysterious Visitor," and the second as "Engineer Cop."
I got the impression that the guy was up there for some reason of his own (watch the sunrise? an architect or executive of the developer etc. getting an early start? - doesn't really matter); saw the two of them, saw the wire, figured out what they were up to, and left them to do it. The actors pass a quick glance between them that seems to imply an unspoken understanding. If he calls the cops, he's the biggest spoilsport in NYC. If he doesn't and Petit fails, then no one (but Jeff) is any the wiser. If he doesn't and Petit succeeds ... well, there's the legend.
I'm guessing he's a guy who worked there and sneaked up there to watch the sunrise view. He didn't look depressed, he was dressed nicely. He didn't alert the authorities because they'd eventually ask him what was his business up there.
My theory is that he works there. He just wanna look at the view! It was likely that he saw the wire, but the image of a man walking on the wire did not conjure up in his mind. He might think they were just construction workers who began to work.
I said the same thing in another thread. I don't know where the suicide theory came from. He looked calm, casual, not jumpy (so to speak) or agitated. Did he even get close enough to the edge to look down?
People who commit suicide aren't always jumpy or agitated, in fact they can sometimes be very calm because they're at peace with what they're about to do.
I have a different explanation. The scene aims to show how much Philippe is determined to go ahead with his plan and is going to stop anyone who would ruin it. Notice that he takes a pipe from the ground and is going to hit the man if he attempts to stop him or report him to the guards.
The movie was a tribute to the Twin Towers as much as it was to Philippe Petit. My take on the mystery man was that he was a representation of the average New Yorker's awe and admiration of the Towers and their builders, and also the one-of-a-kind view from the top. When he stared at Petit (JGL), it looked more like he was thinking "Oh, you're up here admiring the view too. What an awesome city we live in." rather than "What the heck are you doing here?".
The suicide theory by all means makes more sense than anything anyone else has suggested. No, he wasn't just going for the view. This is film we are talking about here.
it also makes sense considering Phillip was considering physically harming the mystery man if he had to and why the mystery man non-verbally responds with no aggression and not much resistance; Phillip saves this man's life without realizing it.
Just watched last night. Yeah, that was my impression too...that he was there to jump off.
Why did he not go through with it?
I'm not an expert at all but the few suicides that I have experience with the person was alone at the end. .. maybe they don't want to risk being talked out of it. .. or don't want to expose someone else to the tragedy of it?
I think he was CIA, or FBI. They had surveillance equipment on the upper level and heard their voices, they knew what they were doing, so only sent one guy, which is why he was looking at the cables, intrigued, he let them continue.