The heavy shield used by the Sasquatch imposes a -1 reduction to ground MP; as such, its speed is reduced from 5/8 down to 4/6, giving it the final in-universe speed of 65 kph.
If there is an error, it is in The Reach's assertion that the -001 moves 63.8 kph; that should read 64.8 to align with all other 4/6 designs.