Aragorn may not have been gentle, but he doesn't seem the bully like Faramir's men in Peter Jackson's version.
Think that the quote you provide is followed by something like, "I tamed him through withholding water and food." Be good, get a treat; be bad and get no fish to eat or something.
I like what
CSteefel suggests (maybe) that Gollum was caught between two forces - his lust for the One Ring and the call from that other ring, Sauron. Or maybe Gollum employed what in mathematics is called a
random walk. Gollum eventually arrives at Mordor, but on the way has pretty much tread every possible path getting there, which later proves very useful to Frodo, especially in the Dead Marshes.