I can see how MaRV technology would make a point defense very difficult (e.g. the old Sprint ABM, THAAD, or Patriot PAC-III). Point defense is a last ditch effort to hit the RV in the last moments of its trajectory. The MaRV can maneuver during the atmospheric reentry phase making point defense aiming much more difficult.

However, Putin's claims that this technology would defeat any known ABM technology don't seem to hold up. The current missiles being deployed in Alaska and soon in Vandenberg are designed to intercept the warheads well above the atmosphere. To maneuver in space, you have to fire thrusters which defeat any decoys you might be using and increase your IR signiture, making it easier to discrimate and engage the RV. To successfully dodge the kinetic kill vehicles, you'd have to do quite a bit of maneuvering, followed by more maneuvering to get back on track for your target. While not impossible, the extra propellant needed for all of that maneuvering cuts into your RV weight.

In addition, MaRV technology doesn't do a thing to help defeat boost phase defenses that are under development.