If the point argued is solely "the speed of light is a huge limitation" (and not: "getting anywhere near the speed of light is a big issue"), I'd say accepting that "even basic much lesser speed is a huge problem" is hardly a refutation of that. Nor is it an argument towards the feasibility of the actual feat being discussed (interstellar travel).

I guess you're technically correct though: the speed of light is not an issue, if 1/10th the speed of light is already unachievable.