NO, it’s not a serious teaser or spoiler of anything. Just goofiness.
Colin was talking about how he’d like to learn about Hook’s mother and see more of him with the two Liams. Adam was the one who cut in to first make the “third Liam” joke, which Colin repeated, so it could mean something, but it could just as easily mean absolutely nothing. You know how it is.
I wouldn’t take this as a teaser about a CS baby name, because nothing about the exchange or the comments before or after it was aimed in that direction. I mean, anything’s possible, but it’s kind of a jump.
And the exchange was definitely done in a joking way, poking fun at the fact that the guy’s got two brothers named Liam. I mean, you never know what might come about in S7, but I don’t think we’ll see 20 Liams ;)
Unless this is @lenfaz reading this, in which case I overheard that they made 20 Liams just for you and sent them to your house so you’d never run out of Liams even when others in the fandom insist on killing them off.
In my opinion, when One Direction (usually Liam) have spoken about control, they aren’t talking about public actions, promotional strategies, and publicity. They are speaking about artistic control and the creative process—songwriting, production—their sound. Did they have more and more writing and involvement with each of their albums? Yes. And it’s extremely important to them. They didn’t get to choose their singles, though. (Consider, too, did they choose their merch? Were they eager to release yet another—was it the fourth??—perfume? Or a 1D make-up line? No.)