grid-style ion drives would destroy themselves pretty quickly at 200KeV energy levels, and assuming helium fuel instead of xenon, the rest mass is 3727 MeV, so that's an isp of only circa sqrt(200KeV/3727MeV)c = 0.007c

Assuming they solve that with some other kind of ion drive, shooting fission products out the back, it would still have a wall plug efficiency <80%, and the underlying fission power source (assuming fusion is impossible) would be <50% efficient at producing electricity, so you get an isp of like sqrt(0.8*0.5*200MeV/(238amu*c^2))c = 0.019c and probably a large non-propellant mass on the vessel. With 99% fuel you're only getting up to 8.7% of the speed of light and there's no significant time dilation. Interstellar travel is probably unavoidably terribly slow, which provides a big defender's advantage, so an expansionist AI would get stopped by other AIs.