I'm saying due to Quote's size he would weigh 160-200 pounds (about 90 kilos) if he had the same density as a human being. Despite the fact that he's demonstrably athletic, he can't swim. Either one of two facts must be true.
1) Someone created a super-battle-robot with the skills and knowledge necessary to adapt to varying conditions, previously unknown weaponry, new and advanced technology unknown at the time of programming, and new and terrifying enemies. They did not forsee him being submerged into liquids and made him unable to even learn to swim.
2) Quote's too heavy to swim. I'm guessing he weighs somewhere around 300-400 pounds (about 180 kilos). Maybe even more. At that density, it doesn't matter how athletic you are, swimming is impossible without artificial assistance of some sort. Yes, people can weigh that much and swim, but they are of the spherical persuasion, so they're not as dense.