I also misread that. The 0.005% is in relation to this:
> In the following analysis we assume that 3I/ATLAS is on its current orbit but vary the time-of-entry into the Solar System (or equivalently the time of perihelion), assuming 3I/ATLAS could have come at any time into the Solar System, and happened to do so such that it came within the observed closest approaches of Venus, Mars and Jupiter. The probability of this is 0.005
So exact same trajectory, but analyzed over a long period of time. If it came any earlier or later, it would almost never get this close to exactly those three planets.
> In the following analysis we assume that 3I/ATLAS is on its current orbit but vary the time-of-entry into the Solar System (or equivalently the time of perihelion), assuming 3I/ATLAS could have come at any time into the Solar System, and happened to do so such that it came within the observed closest approaches of Venus, Mars and Jupiter. The probability of this is 0.005
So exact same trajectory, but analyzed over a long period of time. If it came any earlier or later, it would almost never get this close to exactly those three planets.