Help with Kanto mount, 55" tv, and 24" between studs
It is not uncommon to hang one studs that are 24" apart so.  I have a 60" TV hung on 24" studs.   As long as the steel mount is spanned across two studs and securely fastened to the studs (with lag bolts), you'll be fine.

Edit: 
Well, now that your answer says the specs are only for 16" studs (and after reading the specs, it shows the wall plate is only 21"), then, NO, this won't work obviously.  You'll need a different wall plate that can accomodate the span of two studs.  I would not attempt to make this work unless you get crafty with a welder (it isn't worth it, buy a different plate).  You need it spanned across two studs, with very strong fasteners.  Considering this is a swivel out mount, it will put great stress on your fasteners, and they need to be lag bolts into studs.