That doesn’t explain why Russians have been occupying land in Ukraine for all that time. When an imperialist state conquers territory, it occupies the land in order to legitimize its claim it.
They are there, because Ukraine has been a vassal state to Russia, with its people treated as second-class citizens, for centuries. During that time, they have oscillated back and forth in status from rebellion to re-conquered, many times. This is just the latest wave of Russian oppression intended to crush dissent and re-establish Russian dominance over Ukraine through the russification of Ukrainian culture, language and identity. Wash, rinse, repeat.
All that says, is that you are this close to admitting that Ukraine has been an occupied territory for centuries. Except you are using that fact as a justification for continued occupation, and not a reason for Russia to stop their colonial objectives.