This object is thankfully not coming anywhere close to Earth, but an impact of an object this size with Earth would still not sterilize the biosphere, or even evaporate the oceans.
It'd certainly sterilize the vertebrate part of the biosphere: a significant part of its chemical composition (per the paper) should theoretically be CO and HCN. "Hypervolatiles" is the term the paper uses—primordial evils that can only exist in the coldest outer reaches of the Oort cloud, far away from the star that evaporates them.
I don't know the exact numbers, but for water ice the "frost line" is at about 3 au (between Mars and Jupiter)[0]—the line inside which icy comets and ice moons, like Europa, can't form. Presumably there's analogous zones for the increasingly volatile cryogenic ices, going out into the most distant regions—a solid carbon dioxide line, a carbon monoxide line, a cyanide line... The surface of Pluto, for example, is mostly solid nitrogen, with parts of solid methane and solid carbon monoxide [1].
The KT impactor has been estimated to have been about 10 km in diameter and moving at 20 km/s.
A long-period comet, like an Oort cloud object, might impact at 50 km/s, instead of the 10-20 km/s of a near-Earth asteroid.
The physics might say that the energy might not be enough to literally vaporize the oceans or "sterilize" the biosphere, but the global ecosystem is fragile. This thing dropping on the planet would absolutely cause a mass extinction.
Oh, I didn't say the results wouldn't be utterly catastrophic. It's more a comment on just how surprisingly large an impact would be needed for sterilization.
I don't think anymore absolutely 100% sterilization of all life on Earth is possible, we always end up talking about 99.999999% or similar. With exception of maybe super/hypernova of our Sun which ain't possible, or black hole passing directly through/very close to Earth, tearing apart every single atom making up this planet including all of us on quark level.
Imply that the kinetic energy released upon the impact of such an object, show a group sheltering at the ISS (orbit at an altitude of between 370–460 km (200–250 nmi)) or the Tiangong (orbit between 340 and 450 km (210 and 280 mi) ) would not be likely to survive the impact from ejecta thrown into their orbital altitude...
reply