How Park Ji-sung used to command respect from the London players

In my opinion, it was because he didn't have a coercive attitude at all, which is likely why they respected him instead.
If he had acted high-and-mighty just because he was from Man Utd, given the personalities of those London players, they wouldn't have just sat there regardless of Man Utd or whatever—they'd be thinking about their own national team futures.
It's not like they would have just followed him blindly if he had been too soft, either.
But because the play he showed on the pitch was so dedicated and he was the one stepping up to do all the dirty work, they had no choice but to follow him.
If you're a decent human being.