Because it is, and even subtle differences count here a lot.
If I'm not wrong, People with Russian ethnicity and Ukranian (or Latvian, or Moldavan) citizenship are still allowed to use Airbnb, therefore your former claim is false. Most of the older people living there had born in the USSR in fact and many of them are still allowed to use the platform.
This is not a problem of race or of "Airbnb wants to cancel my culture". This is a consequence of sanctions, that are in turn a consequence of invading a country to start a genocide and destroy and loot as many as possible.
Companies are free to not operate in every country of the planet, and can close their office in North Korea or Russia, or stop doing business with anybody, at any time, by any reason. I can understand that in some countries the boundaries between companies and government are blurred, but is not the case of AirBnb.