That's because it was suggested that Rooney would have to "learn" an entire new role, I replied to that post saying that Giggs had to "learn" it too then.
Some people like cider are intelligent enough to understad the meaning of that, some aren't....
No, the post you replied to was asking the question if he would learn some positional sense and discipline. Plenty of midfielders are plenty good but they aren't good enough to warrant a start for Man Utd in midfield without that skill. You're direct reply to that suggested that Giggs learned it at a very late age, not mentioning that he might have had that ability or at least some big ground work in that area.
Rooney has always been a striker. He has played out wide (very rarely in a traditional winger role that Giggs was used to play) and in middle but only as a cover. Basically because he could be afforded to be chucked out there instead of some other players. Doesn't mean he's very good at it, it means he's good enough for the occasion.
Not only would Rooney be wasted in CM, he wouldn't be good enough. Not unless he completely changes his game. And he won't do that. He isn't the calm and composed fellow that can just stroll around in midfield in a possession based team. He isn't Pirlo or Scholes, players that used to play higher but converted to a deeper role. He could do a Del Piero or a Raúl, playing behind the striker. He's not as clever as them though.
He needs to show more to warrant a place in midfield. I don't think he's good enough. Good enough to play there from time to time just like Cleverley and Jones and Anderson and Giggs but not good enough to start every time like Carrick. Rooney's much better further up the pitch and there's no need to change that.