The advantage is you dont have to do anything.
Eh, still seems like more effort than it's worth, since you'd have to at least keep moving to keep from getting autobooted. And your PVP statistics would go to shit. And not to mention, if I have time to sit and pretend to PVP with a Vita in my hands, I'd probably have more fun, you know, actually playing. That's just me I guess.
I'm sure it's not too long before they start investigating folks with atrocious kill/death ratios to see what they're doing in matches, so I doubt it's a problem. (Even if it is a problem, woohoo, free kills in PVP).
I dunno, maybe I'll try PVPing tonight on my Vita while on my treadmill and see if I get any legendaries. Maybe it'll provide positive reinforcement for exercising.