So, on my way to work this morning, my exhaust clamp snapped, and my pipe fell off (damn brand new 2bros...)... So, Im stuck at work running with just open headers. Is it going to be safe to drive it home (approx 20 miles), or should I bite the bullet and get it towed?

 

Ya, it's safe to ride it home.

 

Yeah, perfectly fine to ride you won't harm the bike in any way whatsoever.....just don't melt your shoe or anything.
You'll feel a loss of power especially in the low end, so to keep the engine/driveline smooth keep the revs up higher than usual.