"Solving" the taxation without representation issue by making DC a state is like "solving" it by exempting DC residents from federal taxation and keeping the status quo. Highly cynical, and it doesn't even have the benefit of being cute like the tax exemption.
For that matter, it's like "solving" school shootings by closing down schools.
Again, there might be measures short of statehood that could solve the taxation without representation issue, but the GOP doesn’t actually want to negotiate a compromise on this issue, so why should the residents of DC have to wait any longer when statehood is the quickest, easiest path to representation?