The person or object holding it up is probably photoshopped out.
This, or the person holding it quickly let go and jumped out of frame while the photographer took the photos.
And let a brand new, still gleaming, just released bike fall over immediately thereafter? I think not. Photoshop FTW.
It’s magic - the same way someone can ride it into the middle of a forest without any pedals!! 
Squirrels
Molepeople, squirrel’s tale would be higher than the rim 
This. All you have to do is take 2 pictures with a camera on a tripod. One with the propped up bike and one with just the background. Then you use parts of the picture without the bike to cover up the prop for a perfect match.
That person is also allowed to catch the bike again…
Mike
Hrmm. Photographer could attach a couple pieces of fishing line to the bike and hold it while taking the picture…
OR, tie fishing line behind the crankset, and attach to a small tent stake in the ground a foot or 2 away from the bike. Bet you would never see it in a picture.
Rod/stick from crank to ground.
Think the 2x pictures mentioned above is probably a pretty good call or just photoshop in general, since I didn’t see any props on there. Mystery solved in my head at least.
Its got a gyroscope in the seat post and is self balancing
You can’t see the prop as your line of sight is completely obstructed by the crank area. No need for photoshop or any post production. Basically any long stick will do, or I guess bike mags actually pay for the rod as they do it a lot.
From CyclingTips a while back,
“If you’re on your own, use a clear perspex rod jammed between the non-drive-side crankbolt and the ground at enough of an angle to hold the bike upright. A stick can also be used as a last resort, as too can a small bike stand (as in the feature image) or a bidon.”
Cobbles
Cobbles and Glue
