I don't think he needs to in order to be an awesome part of Infinite. But, maybe? Seriously though, I don't see how it would make or break anything one way or another.
As others have said, it makes next to zero sense that he'd be participating in any kind of intentional infantry movement, so if he does end up participating in trading fire with enemy forces, it'll almost certainly be in defensive and spontaneous circumstances. He's not like Sgt. Johnson; the last place the captain of the Infinity ought to be is directly on the battlefield, fully vulnerable to enemy attack. They could Star Trek it and have him there anyways, but it'd feel off given the precedent established with starship command in the Halo universe to date. Even leaving that aside, the lowest tiered Spartan IV's are more qualified to participate in battle than Lasky on mere combat prowess.