Taking "float" literally meaning float in water:
It's probably safer than a helicopter? I can't remember the name of the effect, but a helicopter in water automatically flips upside down because the heavy engines are mounted on the top. This causes the majority of deaths in helicopter water landings, even in shallow water, because the occupants can't egress due to disorientation.
The real question is does it flip upside down if it goes belly first into water.
Taking "float" meaning can it land:
The blades in the V280 are connected so one engine can drive both props. This thing can also glide AND/or auto-rotate if needed... so I think it'd be pretty danged safe with a competent pilot.
Tilt rotor aircraft have interconnected gearboxes so that they can fly on a single engine. In case of a dual engine failure in vertical lift mode the autorotation capability is very limited due to low rotor inertia; chance of survival is low from any significant altitude. In case of a dual engine failure in airplane mode it can glide like a regular airplane, but the glide ratio is low and stall speed is high so although in ideal circumstances the pilot might be able to put it down safely the most likely outcome is everyone dies.
The real question is does it flip upside down if it goes belly first into water.
Taking "float" meaning can it land: The blades in the V280 are connected so one engine can drive both props. This thing can also glide AND/or auto-rotate if needed... so I think it'd be pretty danged safe with a competent pilot.