It won't get captured, but if it passes close enough, earth's gravity well could change its course slightly. The final effect of that course change cannot be predicted until we know exactly how close it passes.
Yeah, OK, but it will be a "lossless" encounter, won't it? Maybe not.
Are they concerned that it will exchange momentum with the earth in a way that slows it down (as opposed to speeding it up as happens when we use Jupiter's gravitational field to shoot satellites out to Neptune, etc.)?
(steely)