I dunno, seeing how much Sakurai likes his surprises, if he meant for Spring Man to so obviously be the ARMS fighter, then he wouldn't have approved this whole charade in the first place. Outside of a few incidents in 4, he's generally not one to allow mind games to play out for a significant amount of time, boom, reveal, case closed. Even the
teaser didn't last more than a couple of days, and even then the only hint was done in binary.
There has to be a little more to it than just Spring Man being the ARMS fighter, I feel, but what it is, I'm not sure.
What I'm getting at is this: Spring Man is coming with something, and that something is the actual surprise.